Phosphorescent tetradentate metal complexes having modified emission spectra

ABSTRACT

Multidentate metal complexes useful as phosphorescent emitters in display and lighting applications have the structures as described herein. Multidentate metal complexes and compositions including one or more of the complexes described herein can be useful as emitters in organic light emitting diodes (OLEDs), displays and lighting applications, and photovoltaic devices. Generally, a chemical structural change will affect the electronic structure of the compounds, which thereby affects the optical properties of the compounds (e.g., emission and absorption spectra). Thus, the compounds described herein can be tailored or tuned to a particular emission or absorption energy. In some aspects, the optical properties of the compounds disclosed herein can be tuned by varying the structure of the ligand surrounding the metal center.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application of International Patent Application No. PCT/US2014/052084, filed on Aug. 21, 2014, entitled “PHOSPHORESCENT TETRADENTATE METAL COMPLEXES HAVING MODIFIED EMISSION SPECTRA” which claims priority to U.S. Application Ser. No. 61/868,411 filed on Aug. 21, 2013, entitled “ELECTROPHOSPHORESCENT DEVICES WITH ‘QUANTUM DOT’ LIKE EMISSION” and is a continuation-in-part of U.S. application Ser. No. 14/300,832 filed on Jun. 10, 2014, entitled “PHOSPHORESCENT TETRADENTATE METAL COMPLEXES HAVING MODIFIED EMISSION SPECTRA,” which claims priority to U.S. Application Ser. No. 61/833,091 filed on Jun. 10, 2013, entitled “PHOSPHORESCENT TETRADENTATE METAL COMPLEXES HAVING MODIFIED EMISSION SPECTRA,” all of which are incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to multidentate metal complexes and compositions including the same that can be useful as emitters in display and lighting applications, as well as devices including these complexes and compositions.

BACKGROUND

Compounds capable of absorbing and/or emitting light can be ideally suited for use in a wide variety of optical and electro-optical devices, including, for example, photo-absorbing devices such as solar- and photo-sensitive devices, organic light emitting diodes (OLEDs), photo-emitting devices, or devices capable of both photo-absorption and emission and as markers for bio-applications.

FIG. 1 depicts an example of an OLED. As shown in FIG. 1, OLED 100 may include a layer of indium tin oxide (ITO) as an anode 102, a layer of hole-transporting materials (HTL) 104, a layer of emissive materials (EML) 106 including emitter(s) and host(s), a layer of electron-transporting materials (ETL) 108, and a metal cathode layer 110 on substrate 112. The emission color of OLED 100 may be determined by the emission energy (optical energy gap) of the emitter(s) in the layer of emissive materials.

Much research has been devoted to the discovery and optimization of organic and organometallic materials for using in optical and electro-optical devices such as OLEDs. Generally, research in this area aims to accomplish a number of goals, including improvements in absorption and emission efficiency, as well as improvements in processing ability. Despite significant advances in research devoted to optical and electro-optical materials, many currently available materials exhibit a number of disadvantages, including poor processing ability, inefficient emission or absorption, and less than ideal stability, among others. Thus, a need exists for new materials which exhibit improved performance in optical emitting and absorbing applications.

SUMMARY

Multidentate metal complexes and compositions including one or more of the complexes described herein can be useful as emitters in organic light emitting diodes (OLEDs), displays and lighting applications, and photovoltaic devices.

Generally, a chemical structural change will affect the electronic structure of the compounds, which thereby affects the optical properties of the compounds (e.g., emission and absorption spectra). Thus, the compounds described herein can be tailored or tuned to a particular emission or absorption energy. In some aspects, the optical properties of the compounds disclosed herein can be tuned by varying the structure of the ligand surrounding the metal center. For example, compounds having a ligand with electron donating substituents or electron withdrawing substituents generally exhibit different optical properties, including different emission and absorption spectra.

As described herein, the emission spectra of the compounds can be modified by altering one or more of the substitution groups of the ancillary ligands. In some aspects, one or more features of an emission spectrum becomes narrower or broader, exhibits a blue shift or a red shift, or a combination thereof.

In a first general aspect, a composition includes one or more compounds of the formulas:

wherein, for each of the one or more compounds:

(L¹^L²) represents an emitting portion of the compound,

(L³^L⁴) represents an ancillary portion of the compound,

L¹, L² and L³ each independently represents a substituted or unsubstituted aromatic ring, heterocyclic group, carbene group, or N-heterocyclic carbene,

L⁴ represents a substituted or unsubstituted aromatic ring, heterocyclic group, carbene group, N-heterocyclic carbene, chlorine (Cl), fluorine (F), nitrile, substituted alkyl, substituted alkenyl, or C₃-C₆ alkynyl,

L¹ and L² are linked directly,

L² and L³ are linked directly or through a linking atom A¹, wherein A¹ represents oxygen (O), sulfur (S), nitrogen (N), carbon (C), phosphorous (P), silicon (Si), or boron (B), L³ and L⁴ are unlinked, linked directly, or, when L⁴ represents a substituted or unsubstituted aromatic ring, heterocyclic group, carbene group, or N-heterocyclic carbene, linked through a linking atom A², wherein A² represents oxygen (O), sulfur (S), nitrogen (N), carbon (C), phosphorous (P), silicon (Si), or boron (B),

V¹, V², V³ and V⁴ represent coordinated atoms of L¹, L², L³ or L⁴, respectively, wherein V¹, V², V³ and V⁴ each independently represents nitrogen (N), carbon (C), phosphorous (P), boron (B), or silicon (Si),

M represents platinum (Pt), gold (Au), iridium (Ir), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), mercury (Hg), cadmium (Cd), or zirconium (Zr), and

R^(a), R^(b), R^(c) and R^(d) each independently represents mono-, di-, tri, or tetra-substitution, and each independently represents one or more of hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted mono- or dialkylamino group, a substituted or unsubstituted mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof. In some cases, one or more of R^(a), R^(b), R^(c) and R^(d) may not be hydrogen.

Implementations may include one or more of the following features. In some cases, for example, the polymeric group includes a polyalkylene, a polyether, or a polyester. In certain cases, for at least one of the compounds, at least one of the following is true: R^(a) is fused to L¹, R^(b) is fused to L², R^(c) is fused to L³, and R^(d) is fused to L⁴. The composition, or a compound of the composition, may have a neutral charge.

In a second general aspect, a light emitting device includes the composition of the first general aspect. In some cases, the light emitting device includes an organic light emitting diode. In certain cases, the light emitting device is an organic light emitting diode.

In a third general aspect, a device includes the composition of the first general aspect or the light emitting device of the second general aspect. The device may include, for example, a full color display, a photovoltaic device, or a luminescent or phosphorescent display device. In some cases, the device includes an organic light emitting diode. In certain cases, the device is an organic light emitting diode.

Additional aspects will be set forth in the description which follows. Advantages will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an organic light emitting device (OLED).

FIG. 2 shows emission spectra of PtN1N, PtN1NMe, PtN1N-tBu, PtN1NPh and PtN1NCF₃ in CH₂Cl₂ at room temperature.

FIG. 3 shows emission spectra of PtON6, PtON6-tBu and PtON6Ph in CH₂Cl₂ at room temperature.

FIG. 4 shows emission spectra of PtON1, PtON1Me⁴, PtON1Me⁵, PtON1Me⁶, PtON1-tBu, PtON1Ph, PtON1NMe₂, PtON1F and PtON1CF₃ in CH₂Cl₂ at room temperature.

FIG. 5 shows emission spectra of PtON1Me⁴ in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 6 shows emission spectra of PtON1Me⁵ in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 7 shows emission spectra of PtON1Me⁶ in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 8 shows emission spectra of PtON1-tBu in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 9 shows emission spectra of PtON1NMe₂ in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 10 shows emission spectra of PtON1Ph in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77K.

FIG. 11 shows emission spectra of PtON1F in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 12 shows emission spectra of PtON1CF₃ in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 13 shows emission spectra of PtON1N in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 14 shows emission spectra of PtON1Cz in CH₂Cl₂ at room temperature and in 2-methyl-THF at 77 K.

FIG. 15 shows normalized photoluminescent intensity for Composition A (PtON1) and for Composition B (PtON6).

FIG. 16 shows normalized photoluminescent intensity for Composition A PMMA:(PtON1) and for Composition B PMMA:(PtON6).

FIGS. 17A-17D show emission spectra and chemical structures for PtN1N, PPtN1pyC1, PtN1(acac), and PtN1ppy, respectively, at room temperature (solid lines) and 77K (dotted lines).

FIGS. 18A-18C show electroluminescent spectra and FIG. 18D shows plots of external quantum efficiency vs. brightness for the devices of ITO/PEDOT:PSS/NPD/TAPc/x % PtN1N:26mCPy/PO15/BmPyPB/LiF/Al, where x=2, 7, 14.

FIGS. 19A and 19B show plots of external quantum efficiency vs. current density and luminance at constant current of 20 mA/cm² vs. operational time, respectively, for the devices of ITO/HATCN/NPD/x % PtN1N:CBP/BAlq/Alq3/LiF/Al, where x=6, 10, 20. The initial brightness (L₀) of devices at 20 mA/cm² are presented in the inset of FIG. 19B.

FIG. 20A shows emission spectra of PtON7-t-Bu, PtN1N, PtN7N and PtN8ppy at room temperature; FIG. 20B shows plots of external quantum efficiency vs. brightness; FIG. 20C shows electroluminescent spectra; and FIG. 20D shows color coordinates of devices in CIE chromaticity diagram for PtON7-t-Bu, PtN1N and PtN8ppy in a general device structure of ITO/HATCN/NPD/TAPC/emitter:26mCPy/DPPS/BmPyPB/LiF/Al. The chemical structures of PtON7-t-Bu, PtN7N and PtN8ppy are shown in FIG. 20D. The CIE values of PtN7N are calculated based on its room temperature emission spectrum in a solution of dichloromethane.

DETAILED DESCRIPTION

The present disclosure can be understood more readily by reference to the following detailed description and the Examples included therein. Before the present compounds, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing, example methods and materials are now described.

As used in the specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component” includes mixtures of two or more components.

In some aspects, ranges expressed herein as from “about” one particular value to “about” another particular value include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

Disclosed are the components to be used to prepare the compositions described herein as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods.

As referred to herein, a linking atom can connect two groups such as, for example, a N and C group. The linking atom can optionally, if valency permits, have other chemical moieties attached. For example, in one aspect, an oxygen would not have any other chemical groups attached as the valency is satisfied once it is bonded to two atom (e.g., N or C). In contrast, when carbon is the linking atom, two additional chemical moieties can be attached to the carbon. Suitable chemical moieties include, but are not limited to, hydrogen, hydroxyl, alkyl, alkoxy, ═O, halogen, nitro, amine, amide, thiol, aryl, heteroaryl, cycloalkyl, and heterocyclyl.

The term “cyclic structure” or the like terms used herein refer to any cyclic chemical structure which includes, but is not limited to, aryl, heteroaryl, cycloalkyl, cycloalkenyl, heterocyclyl, carbene, and N-heterocyclic carbene.

As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, and aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, those described below. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, heteroatoms, such as nitrogen, can have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. This disclosure is not intended to be limited in any manner by the permissible substituents of organic compounds. Also, the terms “substitution” or “substituted with” include the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound (e.g., a compound that does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc.). It is also contemplated that, in certain aspects, unless expressly indicated to the contrary, individual substituents can be further optionally substituted (i.e., further substituted or unsubstituted).

In defining various terms, “A¹,” “A²,” “A³,” and “A⁴” are used herein as generic symbols to represent various specific substituents. These symbols can be any substituent, not limited to those disclosed herein, and when they are defined to be certain substituents in one instance, they can, in another instance, be defined as some other substituents.

The term “alkyl” as used herein is a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, and the like. The alkyl group can be cyclic or acyclic. The alkyl group can be branched or unbranched. The alkyl group can also be substituted or unsubstituted. For example, the alkyl group can be substituted with one or more groups including, but not limited to, optionally substituted alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, or thiol, as described herein. A “lower alkyl” group is an alkyl group containing from one to six (e.g., from one to four) carbon atoms.

Throughout the specification “alkyl” is generally used to refer to both unsubstituted alkyl groups and substituted alkyl groups; however, substituted alkyl groups are also specifically referred to herein by identifying the specific substituent(s) on the alkyl group. For example, the term “halogenated alkyl” or “haloalkyl” specifically refers to an alkyl group that is substituted with one or more halide, e.g., fluorine, chlorine, bromine, or iodine. The term “alkoxyalkyl” specifically refers to an alkyl group that is substituted with one or more alkoxy groups, as described below. The term “alkylamino” specifically refers to an alkyl group that is substituted with one or more amino groups, as described below, and the like. When “alkyl” is used in one instance and a specific term such as “alkylalcohol” is used in another, it is not meant to imply that the term “alkyl” does not also refer to specific terms such as “alkylalcohol” and the like.

This practice is also used for other groups described herein. That is, while a term such as “cycloalkyl” refers to both unsubstituted and substituted cycloalkyl moieties, the substituted moieties can, in addition, be specifically identified herein; for example, a particular substituted cycloalkyl can be referred to as e.g., an “alkylcycloalkyl.” Similarly, a substituted alkoxy can be specifically referred to as, e.g., a “halogenated alkoxy,” a particular substituted alkenyl can be, e.g., an “alkenylalcohol,” and the like. Again, the practice of using a general term, such as “cycloalkyl,” and a specific term, such as “alkylcycloalkyl,” is not meant to imply that the general term does not also include the specific term.

The term “cycloalkyl” as used herein is a non-aromatic carbon-based ring composed of at least three carbon atoms. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, and the like. The term “heterocycloalkyl” is a type of cycloalkyl group as defined above, and is included within the meaning of the term “cycloalkyl,” where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkyl group and heterocycloalkyl group can be substituted or unsubstituted. The cycloalkyl group and heterocycloalkyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, or thiol as described herein.

The terms “amine” or “amino” as used herein are represented by the formula NA¹A²A³, where A¹, A², and A³ are independently hydrogen, optionally substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The terms “alkoxy” and “alkoxyl” as used herein to refer to an alkyl or cycloalkyl group bonded through an ether linkage; that is, an “alkoxy” group can be defined as —OA¹ where A¹ is alkyl or cycloalkyl as defined above. “Alkoxy” also includes polymers of alkoxy groups as just described; that is, an alkoxy can be a polyether such as —OA¹-OA² or —OA¹-(OA²)_(a)-OA³, where “a” is an integer of from 1 to 200 and A¹, A², and A³ are each independently alkyl groups, cycloalkyl groups, or a combination thereof.

The term “alkenyl” as used herein is a hydrocarbon group of from 2 to 24 carbon atoms with a structural formula containing at least one carbon-carbon double bond. Asymmetric structures such as (A¹A²)C═C(A³A⁴) are intended to include both the E and Z isomers. This can be presumed in structural formulas herein wherein an asymmetric alkene is present, or it can be explicitly indicated by the bond symbol C═C. The alkenyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol, as described herein.

The term “cycloalkenyl” as used herein is a non-aromatic carbon-based ring composed of at least three carbon atoms and containing at least one carbon-carbon double bound, i.e., C═C. Examples of cycloalkenyl groups include, but are not limited to, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, cyclohexadienyl, norbornenyl, and the like. The term “heterocycloalkenyl” is a type of cycloalkenyl group as defined above, and is included within the meaning of the term “cycloalkenyl,” where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkenyl group and heterocycloalkenyl group can be substituted or unsubstituted. The cycloalkenyl group and heterocycloalkenyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein.

The term “alkynyl” as used herein is a hydrocarbon group of 2 to 24 carbon atoms with a structural formula containing at least one carbon-carbon triple bond. The alkynyl group can be unsubstituted or substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol, as described herein.

The term “cycloalkynyl” as used herein is a non-aromatic carbon-based ring composed of at least seven carbon atoms and containing at least one carbon-carbon triple bond. Examples of cycloalkynyl groups include, but are not limited to, cycloheptynyl, cyclooctynyl, cyclononynyl, and the like. The term “heterocycloalkynyl” is a type of cycloalkenyl group as defined above, and is included within the meaning of the term “cycloalkynyl,” where at least one of the carbon atoms of the ring is replaced with a heteroatom such as, but not limited to, nitrogen, oxygen, sulfur, or phosphorus. The cycloalkynyl group and heterocycloalkynyl group can be substituted or unsubstituted. The cycloalkynyl group and heterocycloalkynyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein.

The term “aryl” as used herein is a group that contains any carbon-based aromatic group including, but not limited to, benzene, naphthalene, phenyl, biphenyl, phenoxybenzene, and the like. The term “aryl” also includes “heteroaryl,” which is defined as a group that contains an aromatic group that has at least one heteroatom incorporated within the ring of the aromatic group. Examples of heteroatoms include, but are not limited to, nitrogen, oxygen, sulfur, and phosphorus. Likewise, the term “non-heteroaryl,” which is also included in the term “aryl,” defines a group that contains an aromatic group that does not contain a heteroatom. The aryl group can be substituted or unsubstituted. The aryl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, azide, nitro, silyl, sulfo-oxo, or thiol as described herein. The term “biaryl” is a specific type of aryl group and is included in the definition of “aryl.” Biaryl refers to two aryl groups that are bound together via a fused ring structure, as in naphthalene, or are attached via one or more carbon-carbon bonds, as in biphenyl.

The term “aldehyde” as used herein is represented by the formula —C(O)H. Throughout this specification “C(O)” is a short hand notation for a carbonyl group, i.e., C═O.

The term “alkylamino” as used herein is represented by the formula —NH(-alkyl) where alkyl is as described herein. Representative examples include, but are not limited to, methylamino group, ethylamino group, propylamino group, isopropylamino group, butylamino group, isobutylamino group, (sec-butyl)amino group, (tert-butyl)amino group, pentylamino group, isopentylamino group, (tert-pentyl)amino group, hexylamino group, and the like.

The term “dialkylamino” as used herein is represented by the formula —N(-alkyl)₂ where alkyl is as described herein. Representative examples include, but are not limited to, dimethylamino group, diethylamino group, dipropylamino group, diisopropylamino group, dibutylamino group, diisobutylamino group, di(sec-butyl)amino group, di(tert-butyl)amino group, dipentylamino group, diisopentylamino group, di(tert-pentyl)amino group, dihexylamino group, N-ethyl-N-methylamino group, N-methyl-N-propylamino group, N-ethyl-N-propylamino group and the like.

The term “carboxylic acid” as used herein is represented by the formula —C(O)OH.

The term “ester” as used herein is represented by the formula —OC(O)A¹ or —C(O)OA¹, where A¹ can be alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl as described herein. The term “polyester” as used herein is represented by the formula -(A¹O(O)C-A²-C(O)O)_(a)— or -(A¹O(O)C-A²-OC(O))_(a)—, where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group described herein and “a” is an integer from 1 to 500. “Polyester” is as the term used to describe a group that is produced by the reaction between a compound having at least two carboxylic acid groups with a compound having at least two hydroxyl groups.

The term “ether” as used herein is represented by the formula A¹OA², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group described herein. The term “polyether” as used herein is represented by the formula -(A¹O-A²O)_(a)—, where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group described herein and “a” is an integer of from 1 to 500. Examples of polyether groups include polyethylene oxide, polypropylene oxide, and polybutylene oxide.

The term “polymeric” includes polyalkylene, polyether, polyester, and other groups with repeating units, such as, but not limited to —(CH₂O)_(n)—CH₃, —(CH₂CH₂O)_(n)—CH₃, —[CH₂CH(CH₃)]_(n)—CH₃, —[CH₂CH(COOCH₃)]_(n)—CH₃, —[CH₂CH(COOCH₂CH₃)]_(n)—CH₃, and —[CH₂CH(COO¹Bu)]_(n)-CH₃, where n is an integer (e.g., n>1 or n>2).

The term “halide” as used herein refers to the halogens fluorine, chlorine, bromine, and iodine.

The term “heterocyclyl,” as used herein refers to single and multi-cyclic non-aromatic ring systems and “heteroaryl as used herein refers to single and multi-cyclic aromatic ring systems: in which at least one of the ring members is other than carbon. The term includes azetidine, dioxane, furan, imidazole, isothiazole, isoxazole, morpholine, oxazole, oxazole, including, 1,2,3-oxadiazole, 1,2,5-oxadiazole and 1,3,4-oxadiazole, piperazine, piperidine, pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, pyrrole, pyrrolidine, tetrahydrofuran, tetrahydropyran, tetrazine, including 1,2,4,5-tetrazine, tetrazole, including 1,2,3,4-tetrazole and 1,2,4,5-tetrazole, thiadiazole, including, 1,2,3-thiadiazole, 1,2,5-thiadiazole, and 1,3,4-thiadiazole, thiazole, thiophene, triazine, including 1,3,5-triazine and 1,2,4-triazine, triazole, including, 1,2,3-triazole, 1,3,4-triazole, and the like.

The term “hydroxyl” as used herein is represented by the formula —OH.

The term “ketone” as used herein is represented by the formula A¹C(O)A², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “azide” as used herein is represented by the formula —N₃.

The term “nitro” as used herein is represented by the formula —NO₂.

The term “nitrile” as used herein is represented by the formula —CN.

The term “silyl” as used herein is represented by the formula —SiA¹A²A³, where A¹, A², and A³ can be, independently, hydrogen or an alkyl, cycloalkyl, alkoxy, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “sulfo-oxo” as used herein is represented by the formulas —S(O)A¹, —S(O)₂A¹, —OS(O)₂A¹, or —OS(O)₂OA¹, where A¹ can be hydrogen or an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. Throughout this specification “S(O)” is a short hand notation for S═O. The term “sulfonyl” is used herein to refer to the sulfo-oxo group represented by the formula —S(O)₂A¹, where A¹ can be hydrogen or an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. The term “sulfone” as used herein is represented by the formula A¹S(O)₂A², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenylcycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein. The term “sulfoxide” as used herein is represented by the formula A¹S(O)A², where A¹ and A² can be, independently, an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “thiol” as used herein is represented by the formula —SH.

“R¹,” “R²,” “R³,” “R^(n),” where n is an integer, as used herein can, independently, possess one or more of the groups listed above. For example, if R¹ is a straight chain alkyl group, one of the hydrogen atoms of the alkyl group can optionally be substituted with a hydroxyl group, an alkoxy group, an alkyl group, a halide, and the like. Depending upon the groups that are selected, a first group can be incorporated within second group or, alternatively, the first group can be pendant (i.e., attached) to the second group. For example, with the phrase “an alkyl group comprising an amino group,” the amino group can be incorporated within the backbone of the alkyl group. Alternatively, the amino group can be attached to the backbone of the alkyl group. The nature of the group(s) that is (are) selected will determine if the first group is embedded or attached to the second group.

Compounds described herein may contain “optionally substituted” moieties. In general, the term “substituted,” whether preceded by the term “optionally” or not, means that one or more hydrogens of the designated moiety are replaced with a suitable substituent. Unless otherwise indicated, an “optionally substituted” group may have a suitable substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position. Combinations of substituents envisioned by this disclosure are preferably those that result in the formation of stable or chemically feasible compounds. In is also contemplated that, in certain aspects, unless expressly indicated to the contrary, individual substituents can be further optionally substituted (i.e., further substituted or unsubstituted).

A structure of a compound may be represented by a formula:

which is understood to be equivalent to a formula:

where n is typically an integer. That is, R^(n) is understood to represent five independent substituents, R^(n(a)), R^(n(b)), R^(n(c)), R^(n(d)), R^(n(e)). By “independent substituents,” it is meant that each R substituent can be independently defined. For example, if in one instance R^(n(a)) is halogen, then R^(n(b)) is not necessarily halogen in that instance.

Several references to R, R¹, R², R³, R⁴, R⁵, R⁶, etc. are made in chemical structures and moieties disclosed and described herein. Any description of R, R¹, R², R³, R⁴, R⁵, R⁶, etc. in the specification is applicable to any structure or moiety reciting R, R¹, R², R³, R⁴, R⁵, R⁶, etc. respectively, unless otherwise noted.

Multidentate (e.g., tetradentate) cyclometalated complexes are described herein. In some cases, such complexes can be incorporated with heptacyclic or higher order materials. In another aspect, such complexes can be useful, for example, in displays and lighting applications.

“Compound” and “complex” are used interchangeably herein. A “composition” includes one or more compounds.

In various aspects, the compounds disclosed herein can include one or more of platinum (Pt) complexes, palladium (Pd) complexes, gold (Au) complexes, iridium (Ir) complexes, rhodium (Rh) complexes, ruthenium (Ru) complexes, iron (Fe) complexes, cobalt (Co) complexes, nickel (Ni) complexes, copper (Cu) complexes, zinc (Zn) complexes, silver (Ag) complexes, mercury (Hg) complexes, cadmium (Cd) complexes, zirconium (Zr) complexes, or other metal complexes not specifically recited herein which are capable of emitting light and are thus useful as an emissive materials in devices.

In one aspect, the present application discloses platinum (Pt), palladium (Pd), gold (Au), iridium (Ir), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), mercury (Hg), cadmium (Cd), and/or zirconium (Zr) complexes that can emit electromagnetic radiation. In another aspect, the emission of the complexes can be tuned (e.g. from ultraviolet to near-infrared), by, for example, modifying the ligand structure. In another aspect, the complexes are emissive over a majority of the visible spectrum. In some examples, the complexes can emit light over a range of from about 400 nm to about 700 nm. In another aspect, the complexes have improved stability and efficiency over traditional emission complexes. In yet another aspect, the complexes can be useful as luminescent labels in, for example, bio-applications, anti-cancer agents, or a combination thereof. In another aspect, the complexes can be useful in light emitting devices, such as, for example, emitters in organic light emitting diodes (OLEDs), compact fluorescent lamps (CFLs), light emitting diodes (LEDs), incandescent lamps, and combinations thereof.

For any of the formulas herein, R, R^(a), R^(b), R^(c), R^(d), R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R1², R¹³ and R¹⁴ can, in various aspects, each independently represent a hydrogen, a deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted acyloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazine group, a substituted silyl group, a polymeric group, or a combination thereof. In some cases, any two or more substitutions can represent the same or a different group. Further, the letters “m”, “n”, “o”, “p”, “q” and “r” can, in various aspects, represent an integer of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 . . . etc., and any two or more letters can represent the same or a different number. In some cases, one or more of R, R^(a), R^(b), R^(c), R^(d), R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R1², R¹³ and R¹⁴ may not be hydrogen.

As described herein, a composition may include one or more compounds of the formulas:

wherein, for each of the one or more compounds:

(L¹^L²) represents an emitting portion of the compound,

(L³^L⁴) represents an ancillary portion of the compound,

L¹, L² and L³ each independently represents a substituted or unsubstituted aromatic ring, heterocyclic group, carbene group, or N-heterocyclic carbene,

L⁴ represents a substituted or unsubstituted aromatic ring, heterocyclic group, carbene group, N-heterocyclic carbene, chlorine (Cl), fluorine (F), nitrile, substituted alkyl, substituted alkenyl, or C₃-C₆ alkynyl,

L¹ and L² are linked directly,

L² and L³ are linked directly or through a linking atom A¹, wherein A¹ represents oxygen (O), sulfur (S), nitrogen (N), carbon (C), phosphorous (P), silicon (Si), or boron (B),

L³ and L⁴ are unlinked, linked directly, or, when L⁴ represents a substituted or unsubstituted aromatic ring, heterocyclic group, carbene group, or N-heterocyclic carbene, linked through a linking atom A², wherein A² represents oxygen (O), sulfur (S), nitrogen (N), carbon (C), phosphorous (P), silicon (Si), or boron (B),

V¹, V², V³ and V⁴ represent coordinated atoms of L¹, L², L³ or L⁴, respectively, wherein V¹, V², V³ and V⁴ each independently represents nitrogen (N), carbon (C), phosphorous (P), boron (B), or silicon (Si),

M represents platinum (Pt), gold (Au), iridium (Ir), rhodium (Rh), ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), mercury (Hg), cadmium (Cd), or zirconium (Zr), and

R^(a), R^(b), R^(c) and R^(d) each independently represents mono-, di-, tri, or tetra-substitution, and each independently represents one or more of hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted mono- or dialkylamino group, a substituted or unsubstituted mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof. In some cases, one or more of R^(a), R^(b), R^(c) and R^(d) may not be hydrogen.

In some cases, one or more of the following is true: R^(a) is fused to ligand L¹, R^(b) is fused to ligand L², R^(c) is fused to ligand L³, and R^(d) is fused to ligand L⁴. In certain cases, the composition, each compound therein, or both are neutral in charge. In some implementations, “polymeric” includes a polyalkylene, a polyether, a polyester, or a combination thereof.

Generally, a chemical structural change will affect the electronic structure of the compounds, which thereby affects the optical properties of the compounds (e.g., emission and absorption spectra). Thus, the compounds described herein can be tailored or tuned to a particular emission or absorption energy. In some aspects, the optical properties of the compounds disclosed herein can be tuned by varying the structure of the ligand surrounding the metal center. For example, compounds having a ligand with electron donating substituents or electron withdrawing substituents generally exhibit different optical properties, including different emission and absorption spectra.

As described herein, the emission spectra of the compounds can be modified by altering one or more of the substitution groups of the ancillary ligands. In some aspects, one or more features of an emission spectrum become narrower or broader, exhibits a blue shift or a red shift, or a combination thereof.

For the formulas disclosed herein,

are intended to illustrate that L and L′ are either linked directly or that L and L′ are linked by a linkage group A, A¹, or A², wherein each of the linkage groups may independently represent oxygen (O), sulfur (S), nitrogen (N), phosphorous (P), carbon (C), silicon (Si), or boron (B). In some cases,

may each independently represent the following:

where R, R¹, and R² each independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

V¹, V², V³ and V⁴ represent atoms coordinated to L¹, L², L³ or L⁴, where V¹, V², V³, and V⁴ may each independently represent nitrogen (N), carbon (C), phosphorous (P), boron (B), or silicon (Si).

For any of the formulas disclosed herein,

may each independently represent the following:

where R, R¹, R² and R³ each independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

For any of the formulas disclosed herein,

may represent the following:

where:

n is an integer, and

R¹, R², R³, and R⁴ each independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

For any of the formulas disclosed herein,

may represent the following:

where R, R¹ and R² each independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

The portion of a tetradentate metal complexes represented as

may represent the following:

where R, R¹, and R² each independently represents mono-, di-, tri, or tetra-substitution, and independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

For any of the formulas disclosed herein,

may each independently represent the following:

where:

m, n, and o each independently represents an integer from 1 to 4 indicating mono-, di-, tri, or tetra-substitution, and

R¹ and R² each independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

For any of the formulas disclosed herein,

may represent the following:

where R¹ and R² each independently represents hydrogen, deuterium, a halogen atom, a hydroxyl group, a thiol group, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted haloalkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfinyl group, a ureido group, a phosphoramide group, a mercapto group, a sulfo group, a carboxyl group, a hydrazino group, a substituted silyl group, a polymeric group, or a combination thereof.

A composition may include one or more of the following:

where all symbols have been previously defined.

In some cases, the compositions disclosed herein include one or more of the following:

where all symbols have been previously defined.

In certain cases, the compositions disclosed herein include one or more of the following:

where all symbols have been previously defined.

In certain cases, the compositions disclosed herein include one or more of the following:

In certain cases, the compositions disclosed herein include one or more of the following:

In still other cases, the compositions disclosed herein include one or more of the following:

In still other cases, the compositions disclosed herein include one or more of the following:

In some implementations, the compositions or compounds disclosed herein include one or more derivatives and/or analogues of the compounds described herein, provided that such compounds exhibit desirable properties and have emission or absorption spectra or both that can be tuned via the selection of appropriate ligands.

The compositions disclosed herein are generally suited for use in a wide variety of optical and electro-optical devices, including, for example, photo-absorbing devices such as solar- and photo-sensitive devices, photovoltaic devices, organic light emitting diodes (OLEDs), photo-emitting devices, or devices capable of both photo-absorption and emission and as markers for bio-applications. Compositions described herein include one or more multidentate metal complexes, or compounds. Thus, in some implementations, a composition includes one multidentate metal complex, and in some implementations, a composition includes two or more multidentate metal complexes.

In some implementations, multidentate metal complexes described herein are combined to cover a range of wavelengths. In one example, FIG. 2 shows emission spectra of PtN1N, PtN1NMe, PtN1N-tBu, PtN1NPh and PtN1NCF₃ in CH₂Cl₂ at room temperature. In another example, FIG. 3 shows emission spectra of PtON6, PtON6-tBu and PtON6Ph in CH₂Cl₂ at room temperature. In yet another example, FIG. 4 shows emission spectra of PtON1, PtON1Me⁴, PtON1Me⁵, PtON1Me⁶, PtON1-tBu, PtON1Ph, PtON1NMe₂, PtON1F and PtON1CF₃ in CH₂Cl₂ at room temperature. Thus, as suggested by FIGS. 2-4, compounds described herein can be used singly or combined selectively as an emissive material to yield a desired wavelength range in an OLED.

In some implementations, the compositions disclosed herein are used as host materials for OLED applications, such as full color displays.

In one aspect, the compositions disclosed herein can be useful in a wide variety of applications, such as, for example, lighting devices. In a further aspect, one or more of the complexes can be useful as host materials for an organic light emitting display device.

In another aspect, the compositions disclosed herein are useful in a variety of applications, for example, as light emitting materials. In a further aspect, the compounds can be useful in organic light emitting diodes (OLEDs), luminescent devices and displays, and other light emitting devices.

In another aspect, the compositions disclosed herein can provide improved efficiency and/or operational lifetimes in lighting devices. In some aspects, the compositions disclosed herein can provide improved efficiency and/or operational lifetimes for organic light emitting devices as compared to conventional materials.

In another aspect, the compositions disclosed herein can be useful as, for example, host materials for OLEDs, lighting applications, and combinations thereof.

In another aspect, the compositions disclosed herein can be prepared using a variety of methods, including, but not limited to those recited in the examples provided herein.

EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary and are not intended to be limiting in scope. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in ° C. or is at ambient temperature, and pressure is at or near atmospheric.

Various methods for the preparation method of the compounds described herein are recited in the examples. These methods are provided to illustrate various methods of preparation, but are not intended to limit any of the methods recited herein. Accordingly, one of skill in the art in possession of this disclosure could readily modify a recited method or utilize a different method to prepare one or more of the compounds described herein. The following aspects are only exemplary and are not intended to be limiting in scope. Temperatures, catalysts, concentrations, reactant compositions, and other process conditions can vary, and one of skill in the art, in possession of this disclosure, could readily select appropriate reactants and conditions for a desired complex.

¹H spectra were recorded at 400 MHz, ¹³C NMR spectra were recorded at 100 MHz on Varian Liquid-State NMR instruments in CDCl₃ or DMSO-d₆ solutions and chemical shifts were referenced to residual protiated solvent. If CDCl₃ was used as solvent, ¹H NMR spectra were recorded with tetramethylsilane (δ=0.00 ppm) as internal reference; ¹³C NMR spectra were recorded with CDCl₃ (δ=77.00 ppm) as internal reference. If DMSO-d₆ was used as solvent, ¹H NMR spectra were recorded with residual H₂O (δ=3.33 ppm) as internal reference; ¹³C NMR spectra were recorded with DMSO-d₆ (δ=39.52 ppm) as internal reference. The following abbreviations (or combinations thereof) were used to explain ¹H NMR multiplicities: s=singlet, d=doublet, t=triplet, q=quartet, p=quintet, m=multiplet, br=broad.

Example 1

Platinum complex PtN1N can be prepared according to the following scheme:

Synthesis of 2-bromo-9H-carbazole 1

4′-bromo-2-nitrobiphenyl (22.40 g, 80.55 mmol) and P(OEt)₃ (150 mL) were added under nitrogen to a three-necked round bottom flask equipped with a magnetic stir bar and a condenser. The mixture was heated to 150-160° C. in an oil bath for 30 hours, cooled to ambient temperature, and the excess P(OEt)₃ was removed by distillation under high vacuum. The residue was recrystallized in toluene to afford the desired product, 2-bromo-9H-carbazole, (8.30 g) as a white crystal. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1) as eluent to obtain the desired product, 2-bromo-9H-carbazole 1 (2.00 g in 52% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 7.17 (t, J=7.6 Hz, 1H), 7.28 (dd, J=8.0, 1.6 Hz, 1H), 7.41 (t, J=7.6 Hz, 1H), 7.49 (d, J=8.4 Hz, 1H), 7.65 (d, J=1.6 Hz, 1H), 8.06 (d, J=8.4 Hz, 1H), 8.11 (d, J=7.6 Hz, 1H), 11.38 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 111.22, 113.50, 118.11, 119.09, 120.36, 121.29, 121.58, 121.79, 121.90, 126.09, 139.89, 140.62. The spectroscopic data is consistent with that previously reported (Pan, J.; Wang, X.; Zhang, Y.; Buchwald, S. L. Org. Lett. 2011, 13, 4974-4976).

Synthesis of 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2

2-bromo-9H-carbazole 1 (8.33 g, 34 mmol, 1.0 eq), 2-bromopyridine (10.61 g, 68 mmol, 2.0 eq), L-proline (0.78 g, 6.8 mmol, 0.2 eq) and K₂CO₃ (11.75 g, 85 mmol, 2.5 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then the tube was taken into a glove box where CuI (0.44 g, 3.4 mmol, 0.1 eq) and DMSO (68 mL) were added. The mixture was bubbled with nitrogen for 10 minutes and then the tube was sealed. The tube was taken out of the glove box and heated to 90° C. in an oil bath. After stirring at 90° C. for 3 days, the mixture was cooled to ambient temperature and quenched with water (250 mL). The mixture was then extracted with ethyl acetate three times and the combined organic layer was washed with water three times, dried over magnesium sulfate, then filtered and washed with ethyl acetate. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (20:1-10:1) as eluent to obtain the desired product, 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2, as an off-white solid (8.53 g in 78% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 7.33 (t, J=7.6 Hz, 1H), 7.45-7.50 (m, 3H), 7.74 (d, J=8.4 Hz, 1H), 7.78 (d, J=8.0 Hz, 1H), 7.95 (d, J=2.0 Hz, 1H), 8.11 (td, J=8.0, 2.0 Hz, 1H), 8.19 (d, J=8.4 Hz, 1H), 8.24 (d, J=7.6 Hz, 1H), 8.72 (dd, J=4.8, 1.6 Hz, 1H). ¹H NMR (CDCl₃, 400 MHz): δ 7.32 (t, J=7.6 Hz, 2H), 7.41-7.47 (m, 2H), 7.60 (d, J=8.0 Hz, 1H), 7.77 (d, J=8.4 Hz, 1H), 7.91-7.95 (m, 2H), 8.01 (d, J=2.0 Hz, 1H), 8.07 (d, J=8.0 Hz, 1H), 8.72-8.73 (m, 1H). ¹³C NMR (CDCl₃, 100 MHz): δ 111.10, 114.35, 119.01, 119.78, 120.21, 121.26, 121.30, 121.61, 123.16, 123.64, 124.06, 126.58, 138.65, 139.60, 140.29, 149.78, 151.26. The spectroscopic data is consistent with that previously reported (Chu, J.-H.; Lin, P.-S.; Lee, Y.-M.; Shen, W.-T., Wu, M.-J. Chem. Eur J. 2011, 17, 13613-13620).

Synthesis of 4′-iodo-2-nitrobiphenyl 3

2-nitrobiphenyl (39.84 g, 200 mmol) and HIO₄.2H₂O (9.71 g, 42.6 mmol, 0.213 eq) were added to a single-necked flask equipped with a magnetic stir bar. Then a mixture of HOAc/H₂O/H₂SO₄ (200 mL/40 mL/6 mL) and I₂ (20.20 g, 79.6 mmol, 0.398 eq) was added independently, after which a condenser was utilized and the mixture was heated to 65-70° C. in an oil bath for 90 hours until the color of I₂ nearly disappeared. Then the mixture was cooled to ambient temperature. Water (500 mL) was added dropwise with the mixture, and the mixture was stirred vigorously. The brown solid was then filtered off and washed with water three times. The collected solid was then dissolved in boiling ethanol (200 mL). The mixture was cooled to 45-50° C. slowly and stirred at that temperature for 3 hours. Then the mixture was cooled to ambient temperature slowly with stirring. The precipitate was then filtered off and washed with a small quantity of ethanol. The solid was dried under reduced pressure to obtain the desired product, 4′-iodo-2-nitrobiphenyl 3, as a gray-white solid (30.52 g in 47% yield). ¹H NMR (CDCl₃, 400 MHz): δ 7.04-7.08 (m, 2H), 7.40 (dd, J=8.0, 1.6 Hz, 1H), 7.51 (td, J=8.0, 1.6 Hz, 1H), 7.63 (td, J=7.6, 1.2 Hz, 1H), 7.75-7.78 (m, 2H), 7.89 (dd, J=8.2, 1.6 Hz, 1H). ¹³C NMR (CDCl₃, 100 MHz): δ 94.26, 124.28, 128.56, 129.69, 131.71, 132.49, 135.33, 136.99, 137.78, 148.91. The spectroscopic data is consistent with that previously reported (Kuethe, J. T.; Childers, K. G. Adv. Synth. Catal. 2008, 350, 1577-1586).

Synthesis of 1-(2′-nitrobiphenyl-4-yl)-1H-pyrazole 4

4′-iodo-2-nitrobiphenyl 3 (9.75 g, 30 mmol, 1.0 eq), 1H-pyrazole (2.45 g, 36 mmol, 1.2 eq) and K₂CO₃ (8.71 g, 63 mmol, 3.1 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then the tube was taken into a glove box, wherein CuI (0.11 g, 0.6 mmol, 0.02 eq), trans-1,2-cyclohexanediamine (0.34 g, 3 mmol, 0.1 eq) and dioxane (30 mL) were added. The mixture was bubbled with nitrogen for 5 minutes and then the tube was sealed. The tube was taken out of the glove box and heated to 105-115° C. in an oil bath. The reaction was monitored by TLC and about 68 hours later the starting material 5 was consumed completely. Then the mixture was cooled to ambient temperature, diluted with ethyl acetate, then filtered and washed with ethyl acetate. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-3:1) as eluent to obtain the desired product, 1-(2′-nitrobiphenyl-4-yl)-1H-pyrazole 4, as a off-white solid (7.5 g in 94% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.57 (t, J=2.0 Hz, 1H), 7.46 (d, J=8.4 Hz, 2H), 7.59-7.65 (m, 2H), 7.75-7.79 (m, 2H), 7.92 (d, J=8.4 Hz, 2H), 7.99-8.01 (m, 1H), 8.56 (d, J=2.4 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 108.14, 118.56, 124.20, 127.88, 128.99, 129.06, 131.83, 133.01, 134.26, 134.62, 139.51, 141.33, 148.82.

Synthesis of 2-(1H-pyrazol-1-yl)-9H-carbazole 5

1-(2′-nitrobiphenyl-4-yl)-1H-pyrazole 4 (7.23 g, 27.26 mmol) was added to a three-necked flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, and then P(OEt)₃ (150 mL) was added under nitrogen. The mixture was stirred in an oil bath at a temperature of 150-165° C. for 24 hours. The mixture was then cooled and the excess P(OEt)₃ was removed by distillation under high vacuum. The residue was recrystallized in ethyl acetate to yield the desired product as a white solid (3.60 g). The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1-2:1) as eluent to obtain an additional crop of the desired product, 2-(1H-pyrazol-1-yl)-9H-carbazole 5 (1.30 g in 77% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.55-6056 (m, 1H), 7.17 (t, J=7.6 Hz, 1H), 7.36-7.40 (m, 1H), 7.48-7.50 (m, 1H), 7.64 (dt, J=8.0, 0.8 Hz, 1H), 7.76 (s, 1H), 7.90 (d, J=2.0 Hz, 1H), 8.11 (d, J=7.6 Hz, 1H), 8.18 (d, J=8.8 Hz, 1H), 8.55 (d, J=2.8 Hz, 1H), 11.40 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 100.97, 107.65, 109.96, 111.01, 118.94, 120.16, 120.74, 120.99, 122.11, 125.55, 127.96, 137.87, 140.11, 140.42, 140.71.

Synthesis of 2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole Ligand N1N

2-(1H-pyrazol-1-yl)-9H-carbazole 5 (3.50 g, 15.0 mmol, 1.0 eq), 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2 (5.82 g, 18 mmol, 1.2 eq), Pd₂(dba)₃ (0.28 g, 0.3 mmol, 0.02 eq), and JohnPhos (2-biphenyl)di-tert-butylphosphine) (0.18 g, 0.6 mmol, 0.04 eq) was added to a dry pressure tube equipped with a magnetic stir bar. The tube was then taken into a glove box. ^(t)BuONa (2.02 g, 21 mmol, 1.4 eq) and dry toluene (60 mL) were added. The mixture was bubbled with nitrogen for 10 minutes and then the tube was sealed. The tube was taken out of the glove box and heated to 95-105° C. in an oil bath. The reaction was monitored by TLC and about 6 hours later the starting material 5 was consumed completely. Then the mixture was cooled to ambient temperature and diluted with ethyl acetate. The mixture was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product, 2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole Ligand N1N, as a brown solid (6829 mg in 96% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.53 (t, J=1.6 Hz, 1H), 7.31-7.35 (m, 1H), 7.42-7.47 (m, 4H), 7.57 (t, J=8.4 Hz, 1H), 7.61 (dd, J=8.0, 1.6 Hz, 1H), 7.70 (d, J=1.6 Hz, 1H), 7.81 (dd, J=8.8, 1.6 Hz, 1H), 7.86 (d, J=1.2 Hz, 1H), 7.90 (d, J=8.4 Hz, 2H), 8.05 (d, J=1.6 Hz, 1H), 8.09 (td, J=8.0, 1.6 Hz, 1H), 8.30 (d, J=7.6 Hz, 1H), 8.38 (d, J=8.4 Hz, 1H), 8.41 (d, J=8.0 Hz, 1H), 8.57-8.60 (m, 2H), 8.67-8.68 (m, 1H). ¹H NMR (CDCl₃, 400 MHz): δ 6.42 (t, J=2.0 Hz, 1H), 7.22-7.26 (m, 1H), 7.28-7.32 (m, 1H), 7.37-7.43 (m, 3H), 7.48-7.52 (m, 2H), 7.61 (dd, J=8.0, 1.6 Hz, 1H), 7.66 (d, J=8.0 Hz, 1H), 7.68 (d, J=1.6 Hz, 1H), 7.76 (d, J=2.0 Hz, 1H), 7.84-7.89 (m, 2H), 7.94 (d, J=2.4 Hz, 1H), 8.04 (d, J=2.0 Hz, 1H), 8.13 (d, J=7.2 Hz, 1H), 8.16-8.20 (m, 2H), 8.31 (d, J=8.0 Hz, 1H), 8.63 (dd, J=4.8, 0.8 Hz, 1H). ¹³C NMR (CDCl₃, 100 MHz): δ 101.22, 107.40, 110.12, 110.64, 111.21, 111.81, 119.00, 120.16, 120.20, 120.24, 120.42, 120.99, 121.40, 121.43, 121.56, 121.72, 122.77, 123.78, 123.97, 126.01, 126.70, 127.21, 135.08, 138.69, 138.70, 140.29, 140.31, 140.88, 141.94, 142.22, 149.77, 151.36.

Synthesis of 2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole Platinum Complex PtN1N

2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole Ligand N1N (1427 mg, 3.0 mmol, 1.0 eq), K₂PtCl₄ (1308 mg, 3.15 mmol, 1.05 eq) and ^(n)Bu₄NBr (97 mg, 0.3 mmol, 0.1 eq) were added to a dry pressure tube equipped with a magnetic stir bar. The tube was then taken into a glove box and acetic acid (180 mL) was added. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The tube was taken out of the glove box and the mixture was stirred at room temperature for 20 hours. Then the mixture was heated to 105-115° C. in an oil bath and stirred at that temperature for three days, cooled to ambient temperature and water (180 mL) was added slowly. After stirring at room temperature for 10 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product, 2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole platinum complex PtN1N, as a yellow solid 872 mg in 44% yield. The product (546 mg) was further purified by sublimation in a sublimator with four zone controllers under high vacuum. The sublimation conditions were: 180° C., 180° C., 140° C., 100° C., 4.6×10⁻⁶ Pa for 0.5 hour; then 200° C., 200° C., 170° C., 140° C., 4.1×10⁻⁶ Pa, 19 hours; then 255° C., 255° C., 210° C., 180° C., 4.1×10⁻⁶ Pa, 1 hour; then 265° C., 260° C., 210° C., 180° C., 4.1×10⁻⁶ Pa, 1.5 hours; then 270° C., 265° C., 210° C., 180° C., 4.1×10⁻⁶ Pa, 93 hours; then 275° C., 265° C., 210° C., 180° C., 4.1×10⁻⁶ Pa, 48 hours. The sublimator was then cooled to ambient temperature and the desired product PtN1N was obtained as yellow solid (295 mg in 54% yield). FIG. 1 shows an emission spectrum of PtN1N in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 6.86 (t, J=2.0 Hz, 1H), 7.30 (t, J=7.6 Hz, 1H), 7.40-7.44 (m, 2H), 7.48-7.52 (m, 2H), 7.70 (d, J=8.4 Hz, 1H), 7.95 (d, J=8.0 Hz, 1H), 8.00 (d, J=8.0 Hz, 1H), 8.07 (d, J=8.0 Hz, 1H), 8.10 (d, J=2.0 Hz, 1H), 8.14 (d, J=8.0 Hz, 1H), 8.20-8.27 (m, 5H), 8.90 (d, J=2.8 Hz, 1H), 9.20 (d, J=5.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 106.00, 107.65, 108.24, 11.58, 113.00, 113.54, 114.40, 115.31, 115.35, 116.47, 116.93, 118.27, 120.19, 120.45, 120.59, 120.91, 122.89, 125.09, 125.59, 126.09, 127.48, 128.87, 137.97, 138.21, 138.27, 139.28, 139.91, 140.23, 143.32, 143.35, 147.26, 151.84. Anal. Calcd. for C₃₂H₁₉N₅Pt: C, 57.48, H, 2.86, N, 10.47; Found: C, 57.29, H, 3.06, N, 10.39.

Example 2

Platinum complex PtN1NMe can be prepared according to the following scheme:

Synthesis of 9-(2′-nitrobiphenyl-4-yl)-2-(1H-pyrazol-1-yl)-9H-carbazole 6

2-(1H-pyrazol-1-yl)-9H-carbazole 5 (1.35 g, 5.78 mmol, 1.0 eq), 4′-iodo-2-nitrobiphenyl 3 (2.26 g, 6.94 mmol, 1.2 eq), K₃PO₄ (2.58 g, 12.14 mmol, 2.1 eq) and CuI (55 mg, 0.29 mmol, 0.05 eq) were added to a dry pressure tube equipped with a magnetic stir bar. The tube was evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, and then 1,2-cyclohexanediamine (0.33 g, 290 uL, 2.89 mmol, 0.5 eq) and dioxane (20 mL) were added. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred in an oil bath at a temperature of 110-120° C. for three days and then cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-3:1), then dichloromethane and methanol (20:1) as eluent to obtain the desired product, 9-(2′-nitrobiphenyl-4-yl)-2-(1H-pyrazol-1-yl)-9H-carbazole 6, as a brown solid (1.98 g in 80% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.55 (t, J=1.6 Hz, 1H), 7.32-7.36 (m, 1H), 7.42 (d, J=8.0 Hz, 1H), 7.45-7.49 (m, 1H), 7.67-7.76 (m, 5H), 7.78-7.81 (m, 3H), 7.84 (dd, J=8.0, 1.6 Hz, 1H), 7.87 (d, J=1.6 Hz, 1H), 8.08 (dd, J=8.4, 1.2 Hz, 1H), 8.29 (d, J=8.0 Hz, 1H), 8.37 (d, J=8.4 Hz, 1H), 8.59 (d, J=1.6 Hz, 1H).

Synthesis of 2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole 7

9-(2′-nitrobiphenyl-4-yl)-2-(1H-pyrazol-1-yl)-9H-carbazole 6 (1.95 g, 4.53 mmol, 1.0 eq) and PPh₃ (3.57 g, 13.59 mmol, 3.0 eq) were added to a three-necked flask equipped with a magnetic stir bar and a condenser. The flask was evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, and then 1,2-dichlorobenzene (25 mL) was added under nitrogen. The mixture was refluxed (175-185° C.) in an oil bath for 24 hours, then cooled, and the solvent was removed by distillation under high vacuum. The residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product, 2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole 7, as a white solid (1.69 g in 94% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.51 (t, J=1.6 Hz, 1H), 7.24 (t, J=7.2 Hz, 1H), 7.30-7.34 (m, 1H), 7.39 (dd, J=8.4, 1.2 Hz, 1H), 7.41-7.47 (m, 3H), 7.57 (d, J=8.0 Hz, 1H), 7.67 (d, J=1.6 Hz, 1H), 7.72 (d, J=1.6 Hz, 1H), 7.79 (dd, J=8.0, 1.6 Hz, 1H), 7.85 (d, J=1.6 Hz, 1H), 8.24 (d, J=7.6 Hz, 1H), 8.29 (d, J=8.0 Hz, 1H), 8.37 (d, J=8.8 Hz, 1H), 8.41 (d, J=8.0 Hz, 1H), 8.56 (d, J=2.0 Hz, 1H), 11.51 (s, 1H).

Synthesis of 9-(4-methylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1NMe

2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole 7 (398 mg, 1.0 mmol, 1.0 eq), Pd₂(dba)₃ (18 mg, 0.02 mmol, 0.02 eq), JohnPhos (12 mg, 0.4 mmol, 0.4 eq) and ^(t)BuONa (154 mg, 1.6 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was then evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, and then dry toluene (3 mL) and 2-bromo-4-methyl-butylpyridine (258 mg, 1.5 mmol, 1.5 eq) were added under nitrogen. The tube was sealed and the mixture was stirred in an oil bath at a temperature of 100-105° C. for 2 days. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1) as eluent to obtain the desired product, 9-(4-methylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1NMe, as a white solid (415 mg in 83% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.39 (s, 3H), 6.50 (t, J=2.4 Hz, 1H), 7.25 (d, J=5.2 Hz, 1H), 7.28-7.32 (m, 1H), 7.39-7.43 (m, 3H), 7.52-7.56 (m, 1H), 7.58 (dd, J=8.1, 1.6 Hz, 1H), 7.67 (d, J=1.6 Hz, 1H), 7.69 (s, 1H), 7.78 (dd, J=8.0, 1.6 Hz, 1H), 7.85 (s, 1H), 7.86 (d, J=8.8 Hz, 1H), 8.00 (d, J=2.0 Hz, 1H), 8.27 (d, J=7.6 Hz, 1H), 8.36 (t, J=8.8 Hz, 2H), 8.48 (d, J=5.2 Hz, 1H), 8.55 (d, J=5.6 Hz, 1H), 8.56 (s, 1H).

Synthesis of 9-(4-methylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Platinum Complex PtN1Nme

9-(4-methylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1NMe (405 mg, 0.81 mmol, 1.0 eq), K₂PtCl₄ (353 mg, 0.85 mmol, 1.05 eq), ^(n)Bu₄NBr (26 mg, 0.081 mmol, 0.1 eq) and acetic acid (49 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was then stirred at room temperature for 24 hours. Then the mixture was heated to 110-115° C. in an oil bath and stirred at that temperature for 4 days, cooled to ambient temperature, and water (60 mL) was added. After stirring at room temperature for 5 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product, 9-(4-methylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole platinum complex PtN1NMe, as a yellow solid (260 mg in 47% yield). FIG. 1 shows an emission spectrum of PtN1NMe in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.46 (s, 3H), 6.85 (t, J=2.4 Hz, 1H), 7.28-7.31 (m, 2H), 7.42 (t, J=7.6 Hz, 1H), 7.48 (d, J=7.6 Hz, 1H), 7.52 (d, J=7.6 Hz, 1H), 7.68 (d, J=8.4 Hz, 1H), 7.94 (d, J=8.0 Hz, 1H), 7.99 (d, J=8.4 Hz, 1H), 8.06 (s, 1H), 8.08 (d, J=1.6 Hz, 1H), 8.10 (d, J=7.6 Hz, 1H), 8.12 (d, J=8.8 Hz, 1H), 8.20 (d, J=4.0 Hz, 1H), 8.21 (d, J=4.0 Hz, 1H), 8.25 (d, J=8.0 Hz, 1H), 8.88 (d, J=2.4 Hz, 1H), 9.05 (d, J=6.4 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 21.03, 105.99, 107.64, 108.36, 111.91, 113.01, 113.50, 114.50, 115.23, 115.24, 116.27, 116.93, 118.25, 120.13, 120.42, 120.92, 121.86, 122.73, 125.12, 125.58, 126.09, 127.43, 128.84, 137.92, 138.25, 138.28, 139.29, 140.15, 143.30, 143.50, 147.03, 151.11, 151.53.

Example 3

Platinum complex PtN1N-tBu can be prepared according to the following scheme:

Synthesis of 9-(4-tert-butylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1N-tBu

2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole 7 (398 mg, 1.0 mmol, 1.0 eq), Pd₂(dba)₃ (46 mg, 0.05 mmol, 0.05 eq), JohnPhos (30 mg, 0.1 mmol, 0.1 eq) and ^(t)BuONa (154 mg, 1.6 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was then evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, then dry toluene (4 mL), dioxane (4 mL), and 2-bromo-4-tert-butylpyridine (418 mg, 2.0 mmol, 2.0 eq) were added under nitrogen. The tube was sealed and the mixture was stirred in an oil bath at a temperature of 95-105° C. for 2 days. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1) as eluent to obtain the desired product, 9-(4-tert-butylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1N-tBu, as a brown solid (470 mg in 88% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 1.28 (s, 9H), 6.52 (t, J=1.6 Hz, 1H), 7.33 (t, J=8.0 Hz, 1H), 7.42-7.45 (m, 3H), 7.50 (d, J=8.4 Hz, 1H), 7.55-7.59 (m, 1H), 7.61 (dd, J=8.0, 2.0 Hz, 1H), 7.69 (d, J=1.6 Hz, 1H), 7.82 (dd, J=8.4, 2.0 Hz, 1H), 7.86-7.88 (m, 2H), 7.91 (d, J=2.0 Hz, 1H), 7.94 (d, J=1.6 Hz, 1H), 8.28 (d, J=8.0 Hz, 1H), 8.36 (d, J=8.8 Hz, 1H), 8.40 (d, J=8.0 Hz, 1H), 8.56 (d, J=5.2 Hz, 1H), 8.59 (d, J=8.4 Hz, 1H), 8.60 (s, 1H). ¹³C NMR (CDCl₃, 100 MHz): δ 30.05, 34.86, 99.67, 104.57, 107.74, 109.80, 111.17, 111.42, 116.16, 119.42, 119.69, 120.44, 120.53, 120.77, 120.82, 121.34, 121.53, 122.07, 122.38, 123.01, 123.03, 126.25, 126.91, 128.12, 134.57, 138.43, 139.76, 139.82, 140.80, 141.16, 141.36, 149.44, 150.58, 163.20.

Synthesis of 9-(4-tert-butylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Platinum Complex PtN1N-tBu

9-(4-tert-butylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1N-tBu (460 mg, 0.87 mmol, 1.0 eq), K₂PtCl₄ (395 mg, 0.95 mmol, 1.1 eq), ^(n)Bu₄NBr (28 mg, 0.087 mmol, 0.1 eq) and acetic acid (52 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred at room temperature for 23 hours. Then the mixture was heated to 105-115° C. in an oil bath and stirred at that temperature for 3 days. The mixture was then cooled to ambient temperature and water (52 mL) was added slowly. After stirring at room temperature for 5 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product, 9-(4-tert-butylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole platinum complex PtN1N-tBu, as a yellow solid (226 mg in 36% yield). FIG. 1 shows an emission spectrum of PtN1N-tBu in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.38 (s, 9H), 6.83 (t, J=2.4 Hz, 1H), 7.30 (t, J=7.6 Hz, 1H), 7.42 (t, J=7.6 Hz, 1H), 7.48-7.53 (m, 3H), 7.69 (d, J=8.0 Hz, 1H), 7.94 (d, J=8.0 Hz, 1H), 8.00 (d, J=8.8 Hz, 1H), 8.06 (d, J=8.0 Hz, 1H), 8.10-8.12 (m, 2H), 8.14 (d, J=8.8 Hz, 1H), 8.22 (d, J=7.6 Hz, 2H), 8.26 (d, J=8.0 Hz, 1H), 8.88 (d, J=2.8 Hz, 1H), 9.08 (d, J=6.4 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 29.64, 35.45, 106.00, 107.63, 108.29, 111.88, 112.71, 112.99, 113.51, 114.07, 115.26, 115.27, 116.90, 118.26, 118.38, 120.34, 120.43, 120.92, 122.81, 125.19, 125.59, 126.10, 127.53, 128.85, 137.98, 138.24, 138.39, 139.29, 140.19, 143.32, 143.50, 147.19, 151.33, 163.22.

Example 4

Platinum complex PtN1NPh can be prepared according to the following scheme:

Synthesis of 9-(4-phenylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1NPh

2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole 7 (398 mg, 1.0 mmol, 1.0 eq), 2-chloro-4-phenylpyridine (228 mg, 1.2 mmol, 1.2 eq), Pd₂(dba)₃ (18 mg, 0.02 mmol, 0.02 eq), JohnPhos (24 mg, 0.8 mmol, 0.8 eq) and ^(t)BuONa (154 mg, 1.6 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was then evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, and then dry toluene (4 mL) was added under nitrogen. The tube was sealed and the mixture was stirred in an oil bath at a temperature of 95-105° C. for 1 day. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product, 9-(4-phenylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1NPh, as a white solid (431 mg in 78% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.50 (t, J=1.2 Hz, 1H), 7.13 (t, J=8.0 Hz, 1H), 7.41-7.46 (m, 5H), 7.51 (d, J=8.0 Hz, 1H), 7.57 (t, J=8.0 Hz, 1H), 7.61 (dd, J=8.4, 0.8 Hz, 1H), 7.68 (t, J=0.8 Hz, 1H), 7.76 (d, J=5.2 Hz, 1H), 7.81 (dd, J=8.4, 1.2 Hz, 1H), 7.87-7.88 (m, 2H), 7.91 (d, J=1.6 Hz, 1H), 7.96 (d, J=8.4 Hz, 1H), 8.08 (s, 1H), 8.21 (s, 1H), 8.27 (d, J=8.0 Hz, 1H), 8.35 (d, J=8.4 Hz, 1H), 8.40 (d, J=7.6 Hz, 1H), 8.58 (d, J=5.6 Hz, 1H), 8.59 (s, 1H), 8.70 (d, J=5.6 Hz, 1H).

Synthesis of 9-(4-phenylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Platinum Complex PtN1NPh

9-(4-phenylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole Ligand N1NPh (420 mg, 0.76 mmol, 1.0 eq), K₂PtCl₄ (332 mg, 0.80 mmol, 1.05 eq), ^(n)Bu₄NBr (25 mg, 0.076 mmol, 0.1 eq) and acetic acid (46 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred at room temperature for 24 hours. Then the mixture was heated to 110-115° C. in an oil bath and stirred at that temperature for 4 days. The mixture was then cooled to ambient temperature and water (60 mL) was added slowly. After stirring at room temperature for 5 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product, 9-(4-phenylpyridin-2-yl)-2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole platinum complex PtN1NPh, as a yellow solid (137 mg in 24% yield). FIG. 1 shows an emission spectrum of PtN1NPh in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 6.83 (t, J=2.4 Hz, 1H), 7.28 (t, J=7.6 Hz, 1H), 7.41 (t, J=7.6 Hz, 1H), 7.46-7.58 (m, 5H), 7.66-7.70 (m, 2H), 7.87-7.89 (m, 2H), 7.93 (d, J=8.0 Hz, 1H), 7.99 (d, J=8.0 Hz, 1H), 8.10 (d, J=2.0 Hz, 1H), 8.13 (d, J=8.0 Hz, 1H), 8.18 (d, J=8.0 Hz, 1H), 8.20 (d, J=8.0 Hz, 2H), 8.24 (d, J=8.4 Hz, 1H), 8.32 (d, J=1.6 Hz, 1H), 8.86 (d, J=2.8 Hz, 1H), 9.18 (d, J=6.4 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 106.03, 107.68, 108.32, 111.79, 113.04, 113.23, 113.58, 114.35, 115.33, 115.38, 117.04, 118.26, 118.31, 120.31, 120.48, 120.94, 122.95, 125.39, 125.62, 126.13, 127.08, 127.58, 128.89, 129.55, 130.23, 136.21, 138.00, 138.34, 138.46, 139.32, 140.19, 143.34, 143.58, 147.65, 150.01, 152.17.

Example 5

Platinum complex PtN1NCF₃ can be prepared according to the following scheme:

Synthesis of 2′-(1H-pyrazol-1-yl)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-2,9′-bicarbazole Ligand N1NCF₃

2′-(1H-pyrazol-1-yl)-9H-2,9′-bicarbazole 7 (420 mg, 1.05 mmol, 1.0 eq), 2-bromo-4-(trifluoromethyl)pyridine (475 mg, 2.10 mmol, 2.0 eq), Pd₂(dba)₃ (48 mg, 0.05 mmol, 0.05 eq), JohnPhos (31 mg, 0.11 mmol, 0.10 eq) and ^(t)BuONa (161 mg, 1.68 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was then evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, and then dry toluene (4 mL) and dioxane (4 mL) were added under nitrogen. The tube was sealed and the mixture was stirred in an oil bath at a temperature of 95-105° C. for 2 days. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1) as eluent to obtain the desired product, 2′-(1H-pyrazol-1-yl)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-2,9′-bicarbazole Ligand N1NCF₃, as a brown solid (467 mg in 82% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.45 (s, 1H), 7.25 (t, J=7.6 Hz, 1H), 7.34-7.43 (m, 3H), 7.51 (t, J=7.6 Hz, 1H), 7.57 (d, J=8.0 Hz, 1H), 7.64 (s, 1H), 7.70 (d, J=5.2 Hz, 1H), 7.76 (dd, J=8.4, 1.2 Hz, 1H), 7.85 (d, J=8.4 Hz, 1H), 7.87 (s, 1H), 8.06 (s, 1H), 8.19 (s, 1H), 8.21 (d, J=7.2 Hz, 1H), 8.29 (d, J=8.8 Hz, 1H), 8.32 (d, J=7.6 Hz, 1H), 8.49 (d, J=8.4 Hz, 1H), 8.52 (d, J=2.4 Hz, 1H), 8.84 (d, J=5.2 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 99.74, 107.71, 109.79, 110.29, 111.17, 111.31, 114.83 (q, J=3.9 Hz), 117.46 (q, J=3.3 Hz), 120.32, 120.43, 120.48, 120.81, 120.84, 121.45, 121.95, 122.01, 122.40, 122.53 (q, J=272.3 Hz), 123.37, 123.41, 126.19, 127.07, 128.01, 134.78, 138.45, 139.46, 139.56, 139.59 (q, J=33.5 Hz), 140.78, 141.14, 141.34, 151.32, 151.52. ¹⁹F NMR (DMSO-d₆, 376 MHz): δ −63.39.

Synthesis of 2′-(1H-pyrazol-1-yl)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-2,9′-bicarbazole Platinum Complex PtN1NCF₃

2′-(1H-pyrazol-1-yl)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-2,9′-bicarbazole Ligand N1NCF₃ (405 mg, 0.745 mmol, 1.0 eq), K₂PtCl₄ (340 mg, 0.82 mmol, 1.1 eq), ^(n)Bu₄NBr (24 mg, 0.0745 mmol, 0.1 eq) and acetic acid (45 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred at room temperature for 21 hours. Then the mixture was heated to 110-115° C. in an oil bath and stirred at that temperature for 3 days. The mixture was then cooled to ambient temperature and water (45 mL) was added slowly. After stirring at room temperature for 5 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane/hexane as eluent to obtain the desired product, 2′-(1H-pyrazol-1-yl)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-2,9′-bicarbazole platinum complex PtN1NCF₃, as a yellow solid (190 mg in 35% yield). FIG. 1 shows an emission spectrum of PtN1NCF₃ in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 500 MHz): δ 6.84 (t, J=2.5 Hz, 1H), 7.31 (t, J=7.5 Hz, 1H), 7.45 (t, J=7.5 Hz, 1H), 7.49-7.55 (m, 2H), 7.64 (d, J=6.5 Hz, 1H), 7.70 (d, J=8.5 Hz, 1H), 7.96 (d, J=8.0 Hz, 1H), 8.00 (d, J=8.5 Hz, 1H), 8.08-8.09 (m, 2H), 8.16 (d, J=8.5 Hz, 1H), 8.22 (t, J=8.0 Hz, 2H), 8.26 (d, J=8.5 Hz, 1H), 8.37 (s, 1H), 8.88 (d, J=2.0 Hz, 1H), 9.39 (d, J=6.5 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 106.03, 107.66, 108.03, 110.77, 112.70 (q, J=4.1 Hz), 113.07, 113.81, 114.12, 115.53, 115.64, 117.08, 118.34, 120.40, 120.56, 120.92, 122.51 (q, J=272.4 Hz), 123.58, 125.43, 125.64, 126.12, 127.88, 128.93, 138.00, 138.12, 138.15, 138.19 (q, J=34.4 Hz), 139.27, 140.27, 143.07, 143.31, 147.65, 153.83. ¹⁹F NMR (DMSO-d₆, 376 MHz): δ −64.04.

Example 6

Platinum complex PtON6-tBu can be prepared according to the following scheme:

Synthesis of 1-(3-methoxyphenyl)-4-phenyl-1H-pyrazole 8

4-phenyl-1H-pyrazole (775 mg, 5.38 mmol, 1.0 eq), 1-iodo-3-methoxybenzene (1510 mg, 768 μL, 6.45 mmol, 1.2 eq), CuI (21 mg, 0.11 mmol, 0.02 eq) and K₂CO₃ (1561 mg, 11.30 mmol, 2.1 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then trans-1,2-cyclohexanediamine (123 mg, 1.08 mmol, 0.20 eq) and dioxane (12 mL) were added. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred in an oil bath at a temperature of 110° C. for three days and then cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product, 1-(3-methoxyphenyl)-4-phenyl-1H-pyrazole 8, as a colorless liquid (1.13 g in 84% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 3.84 (s, 3H), 6.87-6.90 (m, 1H), 7.25 (t, J=7.2 Hz, 1H), 7.38-7.48 (m, 5H), 7.71 (d, J=7.2 Hz, 2H), 8.20 (s, 1H), 9.01 (s, 1H).

Synthesis of 2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 9

A solution of 1-(3-methoxyphenyl)-4-phenyl-1H-pyrazole 8 (1100 mg, 4.39 mmol) in hydrobromic acid (6 mL, 48%) was refluxed (110-120° C.) for 2 days under a nitrogen atmosphere. Then the mixture was cooled to ambient temperature and neutralized with an aqueous solution of K₂CO₃ until gas formation ceased. Then the precipitate was filtered off and washed with water several times and then was dried in air under reduced pressure to afford the product as a brown solid as a mixture of starting material and product (100:31 from the ¹H NMR spectrum), which was used directly for the next steps. The brown solid, 4′-iodo-2-nitrobiphenyl (1209 mg, 3.72 mmol), CuI (30 mg, 0.16 mmol), picolinic acid (38 mg, 0.31 mmol) and K₃PO₄ (1316 mg, 6.20 mmol) were added to a dry Schlenk pressure tube equipped with a magnetic stir bar. The tube was evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, then DMSO (10 mL) was added and the mixture was bubbled with nitrogen for 30 minutes and the tube was sealed. The mixture was heated to 80-90° C. in an oil bath for 3 days. Then the mixture was cooled to ambient temperature, diluted with water, and extracted with ethyl acetate three times. The combined organic layer was washed with water three times, dried over sodium sulfate, then filtered and washed with ethyl acetate. The filtrate was concentrated and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product as a sticky liquid (1.13 g), which was used directly for the next step. PPh₃ (1997 mg, 7.61 mmol, 3.0 eq) was added to a solution of the sticky liquid (1100 mg, 2.54 mmol, 1.0 eq) in 1,2-dichlorobenzene (15 mL) under the protection of nitrogen. The mixture was heated to reflux in an oil bath and stirred at that temperature for 24 hours. The mixture was then cooled and the solvent was removed by distillation under high vacuum. The residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-5:1-3:1) as eluent to obtain the desired product, 2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 9, as a white solid (1000 mg, 57% total yield for the three steps). ¹H NMR (DMSO-d₆, 400 MHz): δ 6.96 (dd, J=8.4, 2.4 Hz, 1H), 7.01 (dd, J=8.0, 2.4 Hz, 1H), 7.16-7.19 (m, 2H), 7.25 (d, J=7.6 Hz, 1H), 7.35-7.42 (m, 3H), 7.48 (d, J=8.0 Hz, 1H), 7.54 (t, J=8.0 Hz, 1H), 7.63 (t, J=2.4 Hz, 1H), 7.68-7.72 (m, 3H), 8.10 (d, J=8.0 Hz, 1H), 8.16 (d, J=7.2 Hz, 1H), 8.19 (s, 1H), 9.05 (s, 1H), 11.26 (s, 1H).

Synthesis of 9-(4-tert-butylpyridin-2-yl)-2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Ligand ON6-tBu

2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 9 (401 mg, 1.0 mmol, 1.0 eq), Pd₂(dba)₃ (46 mg, 0.05 mmol, 0.05 eq), JohnPhos (30 mg, 0.1 mmol, 0.1 eq) and ^(t)BuONa (154 mg, 1.6 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was then evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, then dry toluene (4 mL), dioxane (4 mL) and 2-bromo-4-tert-butylpyridine (418 mg, 2.0 mmol, 2.0 eq) were added under nitrogen. The tube was sealed and the mixture was stirred in an oil bath at a temperature of 100-110° C. for 39 hours. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (20:1-15:1-10:1-5:1) as eluent to obtain the desired product, 9-(4-tert-butylpyridin-2-yl)-2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Ligand ON6-tBu, as a brown solid (460 mg, 86% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 1.24 (s, 9H), 7.04 (dd, J=8.0, 2.6 Hz, 1H), 7.16 (dd, J=8.4, 2.4 Hz, 1H), 7.24 (t, J=7.6 Hz, 1H), 7.32-7.47 (m, 6H), 7.53 (t, J=8.4 Hz, 1H), 7.62 (d, J=1.2 Hz, 1H), 7.66 (t, J=2.0 Hz, 1H), 7.69-7.72 (m, 3H), 7.78 (d, J=8.4 Hz, 1H), 8.19 (s, 1H), 8.24 (d, J=7.6 Hz, 1H), 8.31 (d, J=8.8 Hz, 1H), 8.57 (d, J=5.6 Hz, 1H), 9.05 (s, 1H).

Synthesis of 9-(4-tert-butylpyridin-2-yl)-2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Platinum Complex PtON6-tBu

9-(4-tert-butylpyridin-2-yl)-2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Ligand ON6-tBu (450 mg, 0.84 mmol, 1.0 eq), K₂PtCl₄ (383 mg, 0.92 mmol, 1.1 eq), ^(n)Bu₄NBr (27 mg, 0.084 mmol, 0.1 eq) and acetic acid (50 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred at room temperature for 23 hours. Then the mixture was heated to 105-115° C. in an oil bath and stirred at that temperature for 3 days, cooled to ambient temperature and water (50 mL) was added. After stirring at room temperature for 5 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product, 9-(4-tert-butylpyridin-2-yl)-2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole platinum complex PtON6-tBu, as a yellow solid (525 mg, 86% yield). FIG. 2 shows an emission spectrum of PtON6-tBu in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.40 (s, 9H), 6.99 (d, J=7.6 Hz, 1H), 7.22 (d, J=8.0 Hz, 1H), 7.27 (t, J=8.0 Hz, 1H), 7.36 (t, J=8.0 Hz, 1H), 7.42 (t, J=7.6 Hz, 1H), 7.48-7.56 (m, 5H), 7.91 (t, J=8.0 Hz, 3H), 8.10 (d, J=8.4 Hz, 1H), 8.17-8.19 (m, 2H), 8.67 (s, 1H), 9.25 (d, J=2.4 Hz, 1H), 9.42 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 29.64, 35.46, 98.77, 106.04, 111.18, 112.39, 112.51, 113.26, 114.57, 115.60, 115.72, 118.35, 120.13, 122.88, 123.82, 124.62, 124.73, 125.41, 125.37, 127.33, 127.90, 128.99, 130.80, 136.95, 138.10, 142.01, 146.00, 147.45, 151.96, 152.29, 152.55, 163.03.

Example 7

Platinum complex PtON6Ph can be prepared according to the following scheme:

Synthesis of 2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9-(4-phenylpyridin-2-yl)-9H-carbazole Platinum Complex PtON6Ph

2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 9 (201 mg, 0.5 mmol, 1.0 eq), 2-chloro-4-phenylpyridine (114 mg, 0.6 mmol, 1.2 eq), Pd₂(dba)₃ (9 mg, 0.02 mmol, 0.02 eq), JohnPhos (12 mg, 0.8 mmol, 0.8 eq) and ^(t)BuONa (77 mg, 1.6 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was then evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated twice, then dry toluene (2 mL) was added under nitrogen. The tube was sealed and the mixture was stiffed in an oil bath at a temperature of 95-105° C. for 2 days. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate as eluent to obtain the product as a sticky liquid (209 mg) as a mixture of the starting material, 2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 9, and the desired product, which was used directly for the next step. The sticky liquid (200 mg), K₂PtCl₄ (183 mg, 0.44 mmol), ^(n)Bu₄NBr (13 mg, 0.04 mmol,) and acetic acid (24 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred at room temperature for 18 hours. Then the mixture was heated to 110-120° C. in an oil bath and stirred at that temperature for another 3 days. The mixture was then cooled to ambient temperature and water (25 mL) was added. After stirring at room temperature for 5 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using hexane and dichloromethane (2:3) as eluent to obtain the desired product, 2-(3-(4-phenyl-1H-pyrazol-1-yl)phenoxy)-9-(4-phenylpyridin-2-yl)-9H-carbazole platinum complex PtON6Ph, as a yellow solid (127 mg, 34% total yield for the two steps). FIG. 2 shows an emission spectrum of PtON6Ph in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 7.02 (d, J=8.0 Hz, 1H), 7.24 (d, J=8.4 Hz, 1H), 7.29 (t, J=8.0 Hz, 1H), 7.37 (t, J=7.2 Hz, 1H), 7.44 (t, J=7.2 Hz, 1H), 7.49-7.64 (m, 7H), 7.80 (dd, J=6.4, 1.6 Hz, 1H), 7.91-7.97 (m, 5H), 8.19 (d, J=7.6 Hz, 1H), 8.26 (d, J=8.0 Hz, 1H), 8.44 (d, J=2.0 Hz, 1H), 8.72 (s, 1H) 9.40 (d, J=6.4 Hz, 1H), 9.44 (s, 1H).

Example 8

Platinum complex PtON1 can be prepared according to the following scheme:

Synthesis of 1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 10

1-iodo-3-methoxybenzene (7.15 mL, 60 mmol, 1.0 eq), 3,5-dimethyl-1H-pyrazole (6.92 g, 72 mmol, 1.2 eq), CuI (0.46 g, 2.4 mmol, 0.04 eq) and K₂CO₃ (17.41 g, 126 mmol, 2.1 eq) were added to a dry pressure tube equipped with a magnetic stir bar. Then trans-1,2-cyclohexanediamine (1.37 g, 12 mmol, 0.2 eq) and dioxane (45 mL) were added. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred in an oil bath at a temperature of 110° C. for 3.5 days and then cooled to ambient temperature. The solid was filtered off and washed with ethyl acetate. The filtrate was concentrated under reduced pressure and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (10:1-3:1) as eluent to obtain the desired product, 1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 10, as a brown liquid (7.12 g, 59% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.18 (s, 3H), 2.30 (s, 3H), 3.80 (s, 3H), 6.06 (s, 1H), 6.95 (dd, J=8.0, 2.4 Hz, 1H), 7.02-7.06 (m, 2H), 7.39 (t, J=8.0 Hz, 1H).

Synthesis of 3-(3,5-dimethyl-1H-pyrazol-1-yl)phenol 11

A solution of 1-(3-methoxyphenyl)-3,5-dimethyl-1H-pyrazole 10 (7.10 g, 35.11 mmol) in hydrobromic acid (45 mL, 48%) was refluxed (110-120° C.) for 19 hours a nitrogen atmosphere. Then the mixture was cooled to ambient temperature and neutralized with an aqueous solution of K₂CO₃ until gas formation ceased. Then the precipitate was filtered off and washed with water several times. The collected solid was dried in air to afford the product as a brown solid (6.33 g in 96% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.16 (s, 3H), 2.28 (s, 3H), 6.04 (s, 1H), 6.75-6.77 (m, 1H), 6.86-6.89 (m, 2H), 7.26 (t, J=8.0 Hz, 1H), 9.73 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.29, 13.30, 107.07, 111.10, 113.94, 114.43, 129.71, 138.95, 140.70, 147.57, 157.84.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1

3-(3,5-dimethyl-1H-pyrazol-1-yl)phenol 11 (1.27 g, 6.75 mmol, 1.0 eq), 2-bromo-9-(pyridin-2-yl)-9H-carbazole 2 (2.62 g, 8.10 mmol, 1.2 eq), CuI (0.13 g, 0.675 mmol, 0.1 eq), picolinic acid (0.17 g, 1.35 mmol, 0.2 eq), K₃PO₄ (2.87 g, 13.50 mmol, 2.0 eq) and DMSO (20 mL) were added to a dry pressure vessel equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then vessel was sealed. The mixture was stirred in an oil bath at a temperature of 90-100° C. for 6 days and then cooled to ambient temperature and diluted with ethyl acetate. The solid was filtered off and washed with ethyl acetate. The filtrate was then washed with water three times, dried over sodium sulfate, filtered, and the solvent was removed under reduced pressure. The residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-3:1-2:1) as eluent to obtain the desired product as a colorless sticky liquid (2.80 g in 96% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.11 (s, 3H), 2.24 (s, 3H), 6.01 (s, 1H), 7.02-7.04 (m, 1H), 7.07-7.11 (m, 2H), 7.21-7.24 (m, 1H), 7.33 (t, J=7.6 Hz, 1H), 7.41-7.48 (m, 3H), 7.53 (d, J=2.4 Hz, 1H), 7.76 (d, J=8.8 Hz, 2H), 8.07 (td, J=7.6, 2.0 Hz, 1H), 8.21 (d, J=8.0 Hz, 1H), 8.27 (d, J=8.4 Hz, 1H), 8.66-8.68 (m, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.21, 13.23, 102.42, 107.48, 111.10, 113.25, 113.32, 116.26, 118.25, 119.04, 120.03, 120.19, 121.25, 121.79, 122.13, 123.24, 125.98, 130.41, 139.24, 139.34, 139.51, 139.92, 140.93, 148.08, 149.52, 150.45, 154.77, 157.93.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Platinum Complex PtON1

2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole Ligand ON1 (1340 mg, 3.11 mmol, 1.0 eq), K₂PtCl₄ (1356 mg, 3.27 mmol, 1.05 eq), ^(n)Bu₄NBr (100 mg, 0.31 mmol, 0.1 eq) and acetic acid (187 mL, 60 mL/mmol ligand) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred at room temperature for 48 hours and then in an oil bath at a temperature of 105-115° C. for an additional 3 days. Then mixture was cooled to ambient temperature and water (373 mL, 120 mL/mmol ligand) was added. The mixture was stirred at room temperature for 5 minutes, then the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the title compound as a yellow solid (1057 mg in 55% yield). FIG. 3 shows an emission spectrum of PtON1 in CH₂Cl₂ at room temperature. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.40 (s, 3H), 2.73 (s, 3H), 6.42 (s, 1H), 6.96 (d, J=8.0, 1H), 7.18 (d, J=8.4, 1H), 7.22 (d, J=8.0, 1H), 7.26-7.30 (m, 2H), 7.39 (t, J=7.6, 1H), 7.47 (t, J=7.6 Hz, 1H), 7.85 (d, J=7.6 Hz, 1H), 8.08 (d, J=8.0, 1H), 8.11-8.19 (m, 3H), 9.24 (d, J=4.8 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 14.31, 14.36, 100.17, 107.12, 110.29, 110.97, 112.18, 112.40, 115.07, 115.29, 115.68, 115.71, 119.02, 119.93, 122.85, 124.46, 124.70, 127.95, 137.84, 140.14, 141.87, 141.93, 147.40, 147.98, 149.66, 151.61, 151.99, 153.78.

Example 9

Platinum complex PtON1Me⁴ can be prepared according to the following scheme:

Synthesis of 3,5-dimethyl-1-(3-(2′-nitrobiphenyl-4-yloxy)phenyl)-1H-pyrazole 12

3-(3,5-dimethyl-1H-pyrazol-1-yl)phenol 11 (5.00 g, 26.56 mmol, 1.0 eq), 4′-iodo-2-nitrobiphenyl 3 (10.38 g, 31.92 mmol, 1.2 eq), CuI (0.25 g, 1.33 mmol, 0.05 eq), picolinic acid (0.33 g, 2.66 mmol, 0.1 eq), K₃PO₄ (11.28 g, 53.12 mmol, 2.0 eq) and DMSO (60 mL) were added to a dry pressure tube equipped with a magnetic stir bar. The mixture was bubbled with nitrogen for 30 minutes and then the tube was sealed. The mixture was stirred in an oil bath at a temperature of 80-90° C. for three days and then cooled to ambient temperature. The solid was filtered off and washed with ethyl acetate (250 mL). The filtrate was then washed with water three times, dried over sodium sulfate, filtered, and the solvent was removed under reduced pressure. The residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1-3:1 as eluent to obtain the desired product as a sticky liquid (9.38 g in 92% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.15 (s, 3H), 2.30 (s, 3H), 6.06 (s, 1H), 7.07 (dd, J=8.0, 2.4 Hz, 1H), 7.13-7.16 (m, 3H), 7.30-7.32 (m, 1H), 7.36-7.40 (m, 2H), 7.52 (t, J=8.0, 1H), 7.57 (dd, J=7.6, 1.2 Hz, 1H), 7.59-7.64 (m, 1H), 7.75 (td, J=7.6, 1.2 Hz, 1H), 7.97 (dd, J=8.0, 1.2 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.30, 13.27, 107.63, 114.22, 117.18, 118.91, 118.97, 124.10, 128.81, 129.73, 130.61, 131.84, 132.28, 132.92, 134.33, 139.35, 141.11, 148.20, 148.92, 156.52, 156.67.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13

A solution of 3,5-dimethyl-1-(3-(2′-nitrobiphenyl-4-yloxy)phenyl)-1H-pyrazole 12 (2.19 g, 5.68 mmol, 1.0 eq) and PPh₃ (4.47 g, 17.04 mmol, 3.0 eq) in 1,2-dichlorobenzene (30 mL) was refluxed (175-185° C.) in an oil bath for 24 hours. The mixture was then cooled down and the solvent was removed by distillation under high vacuum. The residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-5:1) as eluent to obtain the desired product, 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13, as a white solid (1.83 g in 92% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.11 (s, 3H), 2.28 (s, 3H), 6.02 (s, 1H), 6.92 (dd, J=8.4, 2.0 Hz, 1H), 7.05 (dd, J=8.4, 2.4 Hz, 1H), 7.10 (t, J=2.0 Hz, 1H), 7.13-7.16 (m, 2H), 7.22-7.25 (m, 1H), 7.32-7.36 (m, 1H), 7.46 (d, J=8.0, 1H), 7.47 (t, J=8.4 Hz, 1H), 8.07 (d, J=7.2 Hz, 1H), 8.12 (d, J=8.4 Hz, 1H), 11.25 (s, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.30, 13.24, 101.46, 107.52, 110.92, 111.10, 113.37, 116.43, 118.09, 118.87, 119.12, 119.88, 121.50, 122.23, 125.23, 130.36, 139.24, 140.17, 140.68, 140.99, 148.10, 154.44, 158.21.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-methylpyridin-2-yl)-9H-carbazole Ligand ON1Me⁴

2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (530 mg, 1.5 mmol, 1.0 eq), Pd₂(dba)₃ (55 mg, 0.06 mmol, 0.04 eq), JohnPhos (36 mg, 0.12 mmol, 0.08 eq) and ^(t)BuONa (231 mg, 2.4 mmol, 1.6 eq) were added to a dry pressure Schlenk tube equipped with a magnetic stir bar. The tube was evacuated and back-filled with nitrogen. The evacuation/back-fill procedure was repeated twice then toluene (6 mL, 4 mL/mmol 13), dioxane (6 mL, 4 mL/mmol 13) and 2-bromo-4-methylpyridine (387 mg, 2.25 mmol, 1.5 eq), were added under nitrogen. The tube was sealed and the mixture was stirred in an oil bath at a temperature of 95-105° C. for 2 days. Then the mixture was cooled to ambient temperature. The solvent was removed under reduced pressure and the residue was purified through column chromatography on silica gel using hexane/ethyl acetate (10:1-4:1) as eluent to obtain the title compound as a colorless solid (628 mg in 94% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.14 (s, 3H), 2.28 (s, 3H), 2.46 (s, 3H), 6.05 (s, 1H), 7.06 (dd, J=8.0, 2.4 Hz, 1H), 7.09-7.13 (m, 2H), 7.26 (dt, J=8.0, 1.2 Hz, 1H), 7.31 (d, J=5.2 Hz, 1H), 7.35 (t, J=7.2 Hz, 1H), 7.44-7.52 (m, 3H), 7.61 (s, 1H), 7.78 (d, J=8.0, 1H), 8.24 (d, J=8.0 Hz, 1H), 8.29 (d, J=8.8 Hz, 1H), 8.53 (d, J=4.8 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.22, 13.22, 20.58, 102.38, 107.48, 111.18, 113.15, 113.29, 116.34, 118.25, 119.48, 119.91, 120.15, 121.12, 121.76, 123.14, 123.16, 125.92, 130.39, 139.24, 139.38, 139.98, 140.93, 148.07, 149.07, 150.47, 150.70, 154.79, 157.90.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-methylpyridin-2-yl)-9H-carbazole Platinum Complex PtON1Me⁴

PtON1Me⁴ was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-methylpyridin-2-yl)-9H-carbazole Ligand ON1Me⁴ (595 mg, 1.34 mmol, 1.0 eq) was reacted with K₂PtCl₂ (583 mg, 1.41 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (42 mg, 0.13 mmol, 0.1 eq) at room temperature for 19 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: dichloromethane) afforded the title compound as a yellow solid (496 mg in 58% yield). FIG. 3 shows an emission spectrum of PtOMe⁴ in CH₂Cl₂ at room temperature. Emission spectra of PtON1Me⁴ at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 5. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.36 (s, 3H), 2.37 (s, 3H), 2.70 (s, 3H), 6.38 (s, 1H), 6.91 (d, J=7.6, 1H), 7.10 (d, J=7.0, 1H), 7.13 (d, J=8.0, 1H), 7.17 (t, J=8.0, 1H), 7.23 (d, J=7.2, 1H), 7.36 (t, J=7.6, 1H), 7.45 (t, J=7.6, 1H), 7.80 (d, J=8.0 Hz, 1H), 7.94 (s, 1H), 8.09 (t, J=8.4 Hz, 2H), 9.03 (d, J=6.0 Hz, 1H). ¹H NMR (CD₂Cl₂, 400 MHz): δ 2.28 (s, 3H), 2.38 (s, 3H), 2.67 (s, 3H), 6.09 (s, 1H), 6.76 (d, J=6.4, 1H), 7.05 (d, J=8.0, 1H), 7.17 (d, J=7.6, 1H), 7.22 (t, J=7.6, 1H), 7.29 (d, J=8.0, 1H), 7.38 (t, J=7.2 Hz, 1H), 7.44 (d, J=7.6 Hz, 1H), 7.81 (d, J=8.0, 1H), 7.88 (s, 1H), 7.96 (d, J=8.0, 1H), 8.06 (d, J=7.6, 1H), 8.96 (d, J=6.4 Hz, 1H). ¹³C NMR (CD₂Cl₂, 100 MHz): δ 14.85, 15.08, 21.59, 100.57, 107.22, 110.31, 111.81, 112.82, 113.15, 115.15, 115.35, 115.95, 116.37, 119.99, 120.19, 122.99, 124.32, 124.67, 129.27, 138.89, 141.95, 143.16, 148.40, 149.13, 149.89, 151.37, 152.76, 153.18, 153.21.

Example 10

Platinum complex PtON1Me⁵ can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(5-methylpyridin-2-yl)-9H-carbazole Ligand ON1Me⁵

Ligand ON1Me⁵ was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (353 mg, 1.0 mmol, 1.0 eq) and 2-bromo-5-methylpyridine (258 mg, 1.5 mmol, 1.5 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1) afforded the title compound as a colorless solid (420 mg in 94% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.12 (s, 3H), 2.25 (s, 3H), 2.39 (s, 3H), 6.03 (s, 1H), 7.04 (dd, J=8.0, 2.4 Hz, 1H), 7.07-7.11 (m, 2H), 7.23 (dd, J=8.0, 2.0 Hz, 1H), 7.32 (t, J=7.6 Hz, 1H), 7.41-7.49 (m, 3H), 7.66 (d, J=8.4 Hz, 1H), 7.71 (d, J=8.0, 1H), 7.89 (dd, J=8.0, 2.0 Hz, 1H), 8.22 (d, J=7.2 Hz, 1H), 8.27 (d, J=8.0 Hz, 1H), 8.50 (d, J=2.0 Hz, 1H). ¹³C NMR (DMSO-d₆, 125 MHz): δ 12.21, 13.23, 17.48, 102.16, 107.49, 110.95, 113.14, 113.26, 116.28, 118.26, 118.64, 119.87, 120.19, 121.04, 121.80, 123.07, 125.92, 130.42, 131.64, 139.25, 139.49, 139.79, 140.05, 140.92, 148.09, 148.10, 149.50, 154.74, 157.95.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(5-methylpyridin-2-yl)-9H-carbazole Platinum Complex PtON1Me⁵

PtON1Me⁵ was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(5-methylpyridin-2-yl)-9H-carbazole Ligand ON1Me⁵ (410 mg, 0.92 mmol, 1.0 eq) was reacted with K₂PtCl₂ (402 mg, 0.97 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (30 mg, 0.092 mmol, 0.1 eq) at room temperature for 19 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: hexane/dichloromethane=1:1) afforded the title compound as a yellow solid (111 mg in 19% yield). FIG. 3 shows an emission spectrum of PtON1Me⁵ at room temperature. Emission spectra of PtON1Me⁵ at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 6. ¹H NMR (CD₂Cl₂, 400 MHz): δ 2.34 (s, 3H), 2.47 (s, 3H), 2.74 (s, 3H), 6.20 (s, 1H), 7.00-7.03 (m, 1H), 7.20-7.26 (m, 3H), 7.35-7.39 (m, 1H), 7.41-7.46 (m, 1H), 7.74 (d, J=9.2 Hz, 1H), 7.77 (dd, J=8.0, 1.6 Hz, 1H), 7.94 (d, J=8.4 Hz, 1H), 8.05 (d, J=8.4 Hz, 2H), 9.09 (s, 1H). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.40 (s, 3H), 2.43 (s, 3H), 2.77 (s, 3H), 6.47 (s, 1H), 6.96 (d, J=8.0 Hz, 1H), 7.17 (d, J=8.4 Hz, 1H), 7.23 (t, J=8.0 Hz, 1H), 7.29 (d, J=8.0 Hz, 1H), 7.40 (d, J=8.4 Hz, 1H), 7.47-7.51 (m, 1H), 7.85 (d, J=8.0 Hz, 1H), 8.02 (dd, J=8.4, 2.0 Hz, 1H), 8.08 (d, J=7.6 Hz, 1H), 8.13 (d, J=8.4 Hz, 1H), 8.15 (d, J=8.4 Hz, 1H), 9.09 (d, J=1.6 Hz, 1H). ¹³C NMR (CD₂Cl₂, 100 MHz): δ 14.72, 15.16, 17.67, 100.21, 107.25, 110.41, 111.44, 112.78, 113.27, 114.93, 115.44, 115.58, 116.30, 120.23, 122.93, 124.33, 124.79, 128.05, 129.20, 138.97, 140.30, 142.11, 143.10, 147.68, 148.41, 149.93, 152.76, 153.20, 153.43.

Example 11

Platinum complex PtON1Me⁶ can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(6-methylpyridin-2-yl)-9H-carbazole Ligand ON1Me⁶

Ligand ON1Me⁶ was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (475 mg, 1.34 mmol, 1.0 eq) and 2-bromo-6-methylpyridine (461 mg, 2.68 mmol, 2.0 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1) afforded the title compound as a brown solid (526 mg in 88% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.11 (s, 3H), 2.24 (s, 3H), 2.48 (s, 3H), 6.02 (s, 1H), 7.07 (td, J=8.0, 2.4 Hz, 2H), 7.14 (t, J=2.0 Hz, 1H), 7.24-7.29 (m, 2H), 7.32 (t, J=7.2 Hz, 1H), 7.43 (t, J=7.2 Hz, 1H), 7.48 (t, J=8.0 Hz, 1H), 7.51 (d, J=2.0, 1H), 7.54 (d, J=8.0 Hz, 1H), 7.76 (d, J=8.0 Hz, 1H), 7.93 (d, J=8.0 Hz, 1H), 8.20 (d, J=7.6 Hz, 1H), 8.25 (d, J=8.0 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.23, 13.23, 23.82, 102.00, 107.51, 111.15, 112.98, 113.68, 115.74, 116.72, 118.42, 119.75, 120.14, 121.13, 121.28, 121.71, 123.23, 125.88, 130.42, 139.23, 139.30, 139.60, 139.93, 140.97, 148.10, 149.75, 155.13, 157.62, 158.34.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(6-methylpyridin-2-yl)-9H-carbazole Platinum Complex PtON1Me⁶

PtON1Me⁶ was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(6-methylpyridin-2-yl)-9H-carbazole Ligand ON1Me⁶ (510 mg, 1.15 mmol, 1.0 eq) was reacted with K₂PtCl₂ (500 mg, 1.20 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (37 mg, 0.115 mmol, 0.1 eq) at room temperature for 23 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: dichloromethane) afforded the title compound as a yellow solid (271 mg in 37% yield). FIG. 3 shows an emission spectrum of PtON1Me⁶ at room temperature. Emission spectra of PtON1Me⁶ at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 6. ¹H NMR (CD₂Cl₂, 400 MHz): δ 2.19 (s, 3H), 2.68 (s, 3H), 3.05 (s, 3H), 6.11 (s, 1H), 7.01 (dd, J=7.6, 2.0 Hz, 1H), 7.08 (d, J=7.6 Hz, 1H), 7.16-7.22 (m, 3H), 7.34 (t, J=8.4 Hz, 1H), 7.42 (t, J=8.4 Hz, 1H), 7.64 (t, J=8.4 Hz, 1H), 7.75 (t, J=8.4 Hz, 1H), 7.96-7.99 (m, 2H), 8.09 (d, J=8.4 Hz, 1H). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.14 (s, 3H), 2.69 (s, 3H), 2.98 (s, 3H), 6.35 (s, 1H), 6.96 (dd, J=8.0, 0.8 Hz, 1H), 7.12 (d, J=8.0 Hz, 1H), 7.20 (t, J=8.0 Hz, 1H), 7.25 (dd, J=7.6, 0.8 Hz, 1H), 7.33 (d, J=7.6 Hz, 1H), 7.37 (t, J=7.6 Hz, 1H), 7.45-7.49 (m, 1H), 7.72 (d, J=8.4 Hz, 1H), 8.00 (t, J=8.0 Hz, 1H), 8.08-8.13 (m, 3H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.84, 13.99, 27.35, 102.71, 107.70, 109.58, 111.71, 112.80, 112.82, 113.41, 114.61, 115.98, 116.51, 120.09, 121.23, 122.89, 124.55, 124.60, 128.77, 138.72, 140.13, 141.31, 142.58, 147.18, 149.46, 149.53, 151.85, 153.31, 161.27.

Example 12

Platinum complex PtON1-tBu can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-tert-butylpyridin-2-yl)-9H-carbazole Ligand ON1-tBu

Ligand ON1-tBu was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (530 mg, 1.5 mmol, 1.0 eq) and 2-bromo-4-tert-butylpyridine (642 mg, 3.0 mmol, 2.0 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1) afforded the title compound as a brown solid (685 mg in 94% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 1.26 (s, 9H), 2.11 (s, 3H), 2.23 (s, 3H), 6.00 (s, 1H), 7.06-7.08 (m, 1H), 7.10 (dd, J=8.0, 2.4 Hz, 1H), 7.14 (t, J=2.4 Hz, 1H), 7.24-7.26 (m, 1H), 7.31 (t, J=7.2 Hz, 1H), 7.38 (d, J=2.0 Hz, 1H), 7.41-7.48 (m, 3H), 7.61 (d, J=1.6, 1H), 7.74 (d, J=8.4 Hz, 1H), 8.20 (d, J=8.0 Hz, 1H), 8.26 (d, J=8.8 Hz, 1H), 8.55 (d, J=4.8 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.21, 13.22, 30.01, 34.81, 101.37, 107.50, 111.11, 113.01, 113.81, 115.78, 116.80, 118.49, 119.27, 119.72, 120.13, 121.11, 121.83, 123.20, 125.90, 130.45, 139.19, 139.43, 139.94, 141.01, 148.07, 149.37, 150.60, 155.32, 157.50, 163.03.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-tert-butylpyridin-2-yl)-9H-carbazole Platinum Complex PtON1-tBu

PtON1-tBu was synthesized according to the procedure of synthesis of PtON1. 9-(4-Tert-butylpyridin-2-yl)-2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Ligand ON1-tBu (635 mg, 1.30 mmol, 1.0 eq) was reacted with K₂PtCl₂ (567 mg, 1.37 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (42 mg, 0.13 mmol, 0.1 eq) at room temperature for 24 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: hexane/dichloromethane=1:1) afforded the title compound as a yellow solid (495 mg in 56% yield). FIG. 3 shows an emission spectrum of PtON1-tBu at room temperature. Emission spectra of PtON1-tBu at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 9. ¹H NMR (CD₂Cl₂, 400 MHz): δ 1.32 (s, 9H), 2.46 (s, 3H), 2.73 (s, 3H), 6.18 (s, 1H), 6.99-7.03 (m, 2H), 7.20-7.26 (m, 3H), 7.38 (t, J=7.6 Hz, 1H), 7.48 (t, J=8.0 Hz, 1H), 7.79 (d, J=7.6 Hz, 1H), 7.94 (d, J=8.0 Hz, 1H), 8.07 (d, J=8.0 Hz, 1H), 8.09 (d, J=1.2 Hz, 1H), 9.08 (d, J=7.2 Hz, 1H). ¹H NMR (DMSO-d₆, 400 MHz): δ 1.32 (s, 9H), 2.43 (s, 3H), 2.75 (s, 3H), 6.44 (s, 1H), 6.95 (d, J=8.0 Hz, 1H), 7.17 (d, J=8.4 Hz, 1H), 7.22 (t, J=8.0 Hz, 1H), 7.28 (d, J=7.6 Hz, 1H), 7.34 (dd, J=6.0, 1.6 Hz, 1H), 7.40 (t, J=7.6 Hz, 1H), 7.50 (t, J=7.6 Hz, 1H), 7.86 (d, J=8.4 Hz, 1H), 8.05 (d, J=1.2 Hz, 1H), 8.11 (d, J=8.0 Hz, 1H), 8.16 (d, J=7.6 Hz, 1H), 9.11 (d, J=6.4 Hz, 1H). ¹³C NMR (CD₂Cl₂, 100 MHz): δ 14.99, 15.15, 30.24, 35.89, 100.32, 107.22, 110.29, 111.78, 112.79, 113.07, 113.21, 114.78, 115.40, 116.33, 116.36, 120.32, 122.94, 124.45, 124.71, 129.28, 139.07, 142.06, 143.23, 148.44, 149.35, 150.01, 152.80, 153.22, 153.41, 163.97.

Example 13

Platinum complex PtON1NMe₂ can be prepared according to the following scheme:

Synthesis of 2-(2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazol-9-yl)-N,N-dimethylpyridin-4-amine Ligand ON1NMe₂

Ligand ON1NMe₂ was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (530 mg, 1.5 mmol, 1.0 eq) and 2-bromo-4-N,N-dimethylaminopyridine (362 mg, 1.8 mmol, 1.2 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=3:1-2:1-1:1) afforded the title compound as a colorless solid (624 mg in 88% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.10 (s, 3H), 2.23 (s, 3H), 2.94 (s, 6H), 5.99 (s, 1H), 6.63 (dd, J=6.0, 1.6 Hz, 1H), 6.74 (d, J=1.6 Hz, 1H), 7.02-7.07 (m, 2H), 7.12 (s, 1H), 7.22 (d, J=8.0 Hz, 1H), 7.27 (t, J=7.6 Hz, 1H), 7.37-7.46 (m, 3H), 7.74 (d, J=8.4 Hz, 1H), 8.15-8.17 (m, 2H), 8.22 (d, J=2.0 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.23, 13.22, 38.89, 101.14, 102.07, 105.77, 107.49, 111.33, 112.71, 113.49, 116.46, 118.27, 119.63, 119.99, 120.64, 121.63, 122.92, 125.70, 130.38, 139.21, 139.73, 140.24, 140.97, 148.07, 148.90, 151.08, 154.84, 156.09, 157.86.

Synthesis of 2-(2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazol-9-yl)-N,N-dimethylpyridin-4-amine Platinum Complex PtON1NMe₂

PtON1NMe₂ was synthesized according to the procedure of synthesis of PtON1. 2-(2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazol-9-yl)-N,N-dimethylpyridin-4-amine Ligand ON1NMe₂ (560 mg, 1.18 mmol, 1.0 eq) was reacted with K₂PtCl₂ (514 mg, 1.24 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (38 mg, 0.118 mmol, 0.1 eq) at room temperature for 24 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: hexane/dichloromethane=1:2) afforded the title compound as a yellow solid (81 mg in 10% yield). FIG. 3 shows an emission spectrum of PtON1NMe₂ at room temperature. Emission spectra of PtON1NMe₂ at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 9. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.45 (s, 3H), 2.74 (s, 3H), 3.08 (s, 6H), 6.42 (s, 1H), 6.66 (dd, J=7.2, 2.0 1H), 6.92 (d, J=8.0 Hz, 1H), 7.10 (d, J=2.0 Hz, 1H), 7.12 (dd, J=8.4, 1.2 Hz, 1H), 7.19 (t, J=8.0 Hz, 1H), 7.25 (d, J=8.0 Hz, 1H), 7.35 (t, J=8.0 Hz, 1H), 7.45 (t, J=8.4 Hz, 1H), 7.81 (dd, J=8.4, 0.8 Hz, 1H), 8.12 (d, J=8.0 Hz, 1H), 8.20 (d, J=7.6 Hz, 1H), 8.67 (d, J=6.4 Hz, 1H). ¹H NMR (CD₂Cl₂, 400 MHz): δ 2.47 (s, 3H), 2.71 (s, 3H), 3.02 (s, 6H), 6.14 (s, 1H), 6.32 (dd, J=7.2, 2.4 1H), 6.97-6.99 (m, 1H), 7.13-7.21 (m, 4H), 7.32 (t, J=7.6 Hz, 1H), 7.40 (t, J=8.0 Hz, 1H), 7.75 (dd, J=8.0, 2.0 Hz, 1H), 8.02 (d, J=8.0 Hz, 2H), 8.69 (dd, J=7.2, 2.0 Hz, 1H). ¹³C NMR (CD₂Cl₂, 100 MHz): δ 14.81, 15.14, 39.69, 96.01, 100.83, 103.58, 107.16, 110.14, 112.51, 112.94, 113.09, 115.00, 115.04, 116.24, 120.12, 122.39, 124.13, 124.25, 129.18, 139.41, 141.85, 143.99, 148.41, 149.53, 149.82, 152.65, 153.16, 153.32, 155.98.

Example 14

Platinum complex PtON1Ph can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-phenylpyridin-2-yl)-9H-carbazole Ligand ON1Ph

Ligand ON1Ph was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (530 mg, 1.5 mmol, 1.0 eq) and 2-chloro-4-phenylpyridine (342 mg, 1.8 mmol, 1.2 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1-3:1) afforded the title compound as a brown solid (725 mg in 95% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.13 (s, 3H), 2.25 (s, 3H), 6.04 (s, 1H), 7.10 (dd, J=8.0, 2.4 Hz, 1H), 7.12-7.15 (m, 2H), 7.25-7.27 (m, 1H), 7.37 (t, J=7.6 Hz, 1H), 7.46-7.57 (m, 6H), 7.79 (dd, J=4.8, 1.6, 1H), 7.85-7.88 (m, 3H), 8.00 (d, J=0.4 Hz, 1H), 8.26 (d, J=7.6 Hz, 1H), 8.31 (d, J=8.8 Hz, 1H), 8.74 (d, J=5.2 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.19, 13.21, 102.13, 107.49, 111.22, 113.20, 113.58, 116.14, 116.49, 118.33, 119.73, 119.95, 120.14, 121.23, 121.77, 123.29, 126.01, 127.10, 129.20, 129.62, 130.37, 136.62, 139.19, 139.44, 140.01, 140.98, 148.06, 150.08, 150.46, 151.29, 155.08, 157.76.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-phenylpyridin-2-yl)-9H-carbazole Platinum Complex PtON1Ph

PtON1Ph was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-phenylpyridin-2-yl)-9H-carbazole Ligand ON1Ph (679 mg, 1.34 mmol, 1.0 eq) was reacted with K₂PtCl₂ (584 mg, 1.41 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (43 mg, 0.134 mmol, 0.1 eq) at room temperature for 19 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: hexane/dichloromethane=1:1) afforded the title compound as a yellow solid (517 mg in 55% yield). FIG. 3 shows an emission spectrum of PtON1Ph at room temperature. Emission spectra of PtON1Ph at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 10. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.35 (s, 3H), 2.70 (s, 3H), 6.35 (s, 1H), 6.96 (d, J=8.0, 1H), 7.18-7.26 (m, 3H), 7.35-7.37 (m, 2H), 7.45-7.48 (m, 4H), 7.71-7.72 (m, 2H), 7.84 (d, J=8.4 Hz, 1H), 8.12 (d, J=7.2 Hz, 1H), 8.18 (s, 1H), 8.22 (d, J=8.4 Hz, 1H), 9.14 (d, J=6.4 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 14.32, 14.35, 100.17, 107.15, 110.29, 111.18, 112.23, 112.38, 112.42, 115.04, 115.31, 115.69, 116.63, 120.02, 122.90, 124.72, 126.96, 128.01, 129.37, 130.11, 136.08, 137.99, 141.88, 142.09, 147.41, 148.26, 149.61, 150.15, 151.64, 152.01, 153.99.

Example 15

Platinum complex PtON1F can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-fluoropyridin-2-yl)-9H-carbazole Ligand ON1F

Ligand ON1F was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (565 mg, 1.6 mmol, 1.0 eq) and 2-bromo-4-fluoropyridine (563 mg, 3.2 mmol, 2.0 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1-4:1) afforded the title compound as a brown solid (643 mg in 90% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.10 (s, 3H), 2.24 (s, 3H), 6.00 (s, 1H), 7.03 (dd, J=8.4, 2.4 Hz, 1H), 7.08-7.10 (m, 2H), 7.22 (d, J=8.0 Hz, 1H), 7.32-7.39 (m, 2H), 7.43 (d, J=7.6 Hz, 1H), 7.46 (d, J=8.4 Hz, 1H), 7.61 (d, J=2.0 Hz, 1H), 7.71 (dd, J=10.0, 1.6 Hz, 1H), 7.82 (d, J=8.4 Hz, 1H), 8.20 (d, J=7.6 Hz, 1H), 8.25 (d, J=8.4 Hz, 1H), 8.68 (dd, J=8.8, 5.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.20, 13.21, 102.95, 106.76 (d, J=20.3 Hz), 107.47, 110.11 (d, J=16.0 Hz), 111.37, 113.24, 113.67, 116.24, 118.24, 120.18, 120.20, 121.60, 121.74, 123.43, 126.11, 130.37, 139.12, 139.22, 139.77, 140.94, 148.07, 151.98 (d, J=8.8 Hz), 152.69 (d, J=10.6 Hz), 154.83, 157.95, 169.56 (d, J=258.8 Hz). ¹⁹F NMR (DMSO-d₆, 376 MHz): δ −99.56-99.49 (m, 1F).

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-fluoropyridin-2-yl)-9H-carbazole Platinum Complex PtON1F

PtON1F was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-fluoropyridin-2-yl)-9H-carbazole Ligand ON1F (600 mg, 1.34 mmol, 1.0 eq) was reacted with K₂PtCl₂ (583 mg, 1.40 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (43 mg, 0.13 mmol, 0.1 eq) at room temperature for 22 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: dichloromethane) afforded the title compound as a yellow solid (81 mg in 10% yield). FIG. 3 shows an emission spectrum of PtON1F at room temperature. Emission spectra of PtON1F at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 11. ¹H NMR (DMSO-d₆, 400 MHz): δ 2.43 (s, 3H), 2.76 (s, 3H), 6.46 (s, 1H), 6.96 (d, J=8.0 Hz, 1H), 7.20 (d, J=8.8 Hz, 1H), 7.24 (d, J=8.4 Hz, 1H), 7.28-7.31 (m, 2H), 7.43 (t, J=7.6 Hz, 1H), 7.51 (t, J=8.0 Hz, 1H), 7.87 (d, J=8.4 Hz, 1H), 7.98 (dd, J=10.4, 2.4 Hz, 1H), 8.15 (d, J=8.4 Hz, 2H), 9.30 (t, J=6.8 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 14.32, 100.33, 102.80 (d, J=23.9 Hz), 107.18, 108.09 (d, J=19.8 Hz), 110.34, 110.52, 112.42, 112.45, 115.17, 115.33, 115.77, 119.98, 123.33, 124.76, 128.16, 137.77, 141.80, 142.01, 147.31, 149.70, 150.08 (d, J=11.8 Hz), 151.67, 151.91, 156.71 (d, J=10.1 Hz), 168.86 (d, J=262.5 Hz). ¹⁹F NMR (DMSO-d₆, 376 MHz): δ −96.41-−96.34 (m, 1F).

Example 16

Platinum complex PtON1CF₃ can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-carbazole Ligand ON1CF₃

Ligand ON1CF₃ was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (707 mg, 2.0 mmol, 1.0 eq) and 2-bromo-4-(trifluoromethyl)pyridine (904 mg, 4.0 mmol, 2.0 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1) afforded the title compound as a brown solid (962 mg in 96% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.13 (s, 3H), 2.26 (s, 3H), 6.04 (s, 1H), 7.08 (dd, J=8.0, 2.4 Hz, 1H), 7.12-7.15 (m, 2H), 7.25-7.27 (m, 1H), 7.38 (t, J=7.6 Hz, 1H), 7.48 (t, J=8.0 Hz, 2H), 7.58 (d, J=1.6 Hz, 1H), 7.81-7.83 (m, 2H), 8.10 (s, 1H), 8.25 (d, J=7.6 Hz, 1H), 8.30 (d, J=8.8 Hz, 1H), 8.95 (d, J=4.8 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.16, 13.18, 102.47, 107.46, 111.09, 113.43, 113.71, 114.52 (q, J=3.9 Hz), 116.37, 117.37 (q, J=2.7 Hz), 118.32, 120.25, 121.77, 121.81, 122.55 (q, J=272.5 Hz), 123.59, 126.16, 130.35, 139.09, 139.19, 139.56 (q, J=34.7 Hz), 139.73, 140.98, 148.06, 151.32, 151.53, 155.05, 157.75. ¹⁹F NMR (DMSO-d₆, 376 MHz): δ −63.32.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-carbazole Platinum Complex PtON1CF₃

PtON1CF₃ was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(4-(trifluoromethyl)pyridin-2-yl)-9H-carbazole Ligand ON1CF₃ (900 mg, 1.81 mmol, 1.0 eq) was reacted with K₂PtCl₂ (787 mg, 1.90 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (58 mg, 0.18 mmol, 0.1 eq) at room temperature for 22 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: hexane/dichloromethane=1:1) afforded the title compound as a yellow solid (720 mg in 58% yield). FIG. 3 shows an emission spectrum of PtON1CF₃ at room temperature. Emission spectra of PtON1CF₃ at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 12. ¹H NMR (CD₂Cl₂, 400 MHz): δ 2.41 (s, 3H), 2.72 (s, 3H), 6.17 (s, 1H), 7.03-7.06 (m, 1H), 7.11 (d, J=5.6 Hz, 1H), 7.18-7.25 (m, 2H), 7.31 (dd, J=8.0, 1.6 Hz, 1H), 7.41-7.50 (m, 2H), 7.80 (dd, J=8.4, 1.6 Hz, 1H), 7.93 (d, J=8.4 Hz, 1H), 8.07 (d, J=7.6 Hz, 1H), 8.36 (s, 1H), 9.39 (d, J=6.4 Hz, 1H). ¹³C NMR (CD₂Cl₂, 100 MHz): δ 14.97, 15.14, 100.19, 107.38, 110.48, 110.49, 122.74 (q, J=3.7 Hz), 113.36, 113.43, 113.49 (q, J=2.6 Hz), 114.76, 115.79, 116.57, 120.57, 122.90 (q, J=272.4 Hz), 124.03, 124.92, 125.19, 129.77, 138.56, 140.11 (q, J=35.5 Hz), 142.31, 142.56, 148.34, 149.87, 150.00, 152.96, 153.01, 155.49. ¹⁹F NMR (DMSO-d₆, 376 MHz): δ −64.10.

Example 17

Platinum complex PtON1N can be prepared according to the following scheme:

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyrimidin-2-yl)-9H-carbazole Ligand ON1N

Ligand ON1N was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (707 mg, 2.0 mmol, 1.0 eq) and 2-bromopyrimidine (636 mg, 4.0 mmol, 2.0 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-5:1-3:1) afforded the title compound as a brown solid (814 mg in 94% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.11 (s, 3H), 2.27 (s, 3H), 6.01 (s, 1H), 7.06 (dd, J=8.0, 2.4 Hz, 1H), 7.12 (t, J=2.0 Hz, 1H), 7.15 (dd, J=8.4, 2.0 Hz, 1H), 7.23-7.26 (m, 1H), 7.37-7.40 (m, 2H), 7.46-7.52 (m, 2H), 8.19 (d, J=8.0 Hz, 1H), 7.25 (d, J=7.6 Hz, 1H), 8.59 (d, J=2.4 Hz, 1H), 8.79 (d, J=8.4 Hz, 1H), 8.93 (d, J=4.4 Hz, 2H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.25, 13.22, 107.47, 107.67, 113.10, 114.61, 116.12, 116.16, 117.19, 118.20, 119.69, 121.16, 121.57, 122.60, 124.62, 126.31, 130.43, 138.86, 139.25, 139.33, 140.97, 148.07, 154.68, 158.05, 158.12, 158.63.

Synthesis of 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyrimidin-2-yl)-9H-carbazole Platinum Complex PtON1N

PtON1N was synthesized according to the procedure of synthesis of PtON1. 2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9-(pyrimidin-2-yl)-9H-carbazole Ligand ON1N (770 mg, 1.78 mmol, 1.0 eq) was reacted with K₂PtCl₂ (776 mg, 1.87 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (57 mg, 0.18 mmol, 0.1 eq) at room temperature for 20 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: dichloromethane) afforded the title compound as a yellow solid (433 mg in 39% yield). Emission spectra of PtON1N at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 13. ¹H NMR (CD₂Cl₂, 400 MHz): δ 2.32 (s, 3H), 2.76 (s, 3H), 6.44 (s, 1H), 6.98 (d, J=7.6 Hz, 1H), 7.22-7.26 (m, 2H), 7.30 (d, J=8.0 Hz, 1H), 7.37 (t, J=6.0 Hz, 1H), 7.41 (t, J=7.6 Hz, 1H), 7.49 (d, J=8.0 Hz, 1H), 7.90 (d, J=8.4 Hz, 1H), 8.12 (d, J=7.6 Hz, 1H), 8.80 (d, J=8.0 Hz, 1H), 9.14-9.16 (m, 1H), 9.51-9.52 (m, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 14.33, 99.67, 107.05, 110.51, 110.89, 112.28, 112.72, 114.92, 115.45, 116.20, 118.99, 119.40, 123.26, 124.63, 124.90, 127.59, 137.90, 140.97, 142.04, 147.40, 149.84, 151.35, 151.51, 151.67, 159.30, 162.97.

Example 18

Platinum complex PtON1Cz can be prepared according to the following scheme:

Synthesis of 9-(4-(9H-carbazol-9-ylpyridin-2-yl)-2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Ligand ON1N

Ligand ON1Cz was synthesized according to the procedure of synthesis of Ligand ON1Me⁴ using 2-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole 13 (589 mg, 1.66 mmol, 1.0 eq) and 9-(2-chloropyridin-4-yl)-9H-carbazole (560 mg, 2.0 mmol, 1.2 eq). Purification of the crude product by flash chromatography on silica gel (eluent: hexane/ethyl acetate=10:1-3:1) afforded the title compound as a brown solid (958 mg in 97% yield). ¹H NMR (DMSO-d₆, 400 MHz): δ 2.07 (s, 3H), 2.17 (s, 3H), 5.95 (s, 1H), 7.01 (dd, J=7.6, 2.4 Hz, 1H), 7.06-7.09 (m, 2H), 7.15-7.18 (m, 1H), 7.27-7.32 (m, 3H), 7.35-7.43 (m, 4H), 7.67 (d, J=8.4 Hz, 2H), 7.72 (d, J=2.0 Hz, 1H), 7.75 (dd, J=5.6, 2.0 Hz, 1H), 7.89 (d, J=8.8 Hz, 1H), 7.91 (d, J=2.0 Hz, 1H), 8.17-8.21 (m, 3H), 8.24 (d, J=8.8 Hz, 1H), 8.87 (d, J=5.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 12.16, 13.21, 103.03, 107.44, 110.16, 111.38, 113.08, 113.63, 115.07, 116.06, 118.16, 118.73, 120.21, 120.33, 120.65, 121.18, 121.45, 121.76, 123.49, 123.63, 126.08, 126.57, 130.35, 138.94, 139.16, 139.38, 140.04, 140.93, 147.11, 148.04, 151.38, 152.44, 154.68, 158.04.

Synthesis of 9-(4-(9H-carbazol-9-yl)pyridin-2-yl)-2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Platinum Complex PtON1N

PtON1Cz was synthesized according to the procedure of synthesis of PtON1. 9-(4-(9H-carbazol-9-yl)pyridin-2-yl)-2-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy)-9H-carbazole Ligand ON1Cz (910 mg, 1.53 mmol, 1.0 eq) was reacted with K₂PtCl₂ (672 mg, 1.60 mmol, 1.05 eq) in the presence of ^(n)Bu₄NBr (49 mg, 0.15 mmol, 0.1 eq) at room temperature for 18 hours and then at 105-115° C. for an additional 3 days. Purification of the crude product by flash chromatography on silica gel (eluent: dichloromethane/hexane=2:1) afforded the title compound as a orange solid (617 mg in 51% yield). Emission spectra of PtON1Cz at room temperature in CH₂Cl₂ and at 77 K in 2-methyl-THF are shown in FIG. 14. ¹H NMR (DMSO-d₆, 400 MHz): 2.56 (s, 3H), 2.77 (s, 3H), 6.48 (s, 1H), 6.98 (d, J=8.0 Hz, 1H), 7.21 (d, J=8.0 Hz, 1H), 7.25 (d, J=8.0 Hz, 1H), 7.20-7.44 (m, 5H), 7.54 (d, J=7.6 Hz, 2H), 7.70 (dd, J=6.8, 2.0 Hz, 1H), 7.85 (d, J=8.0 Hz, 3H), 8.13 (d, J=7.6 Hz, 1H), 8.22-8.28 (m, 4H), 9.43 (d, J=6.0 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 100.44, 107.19, 110.35, 110.45, 110.91, 111.15, 112.33, 112.48, 114.90, 115.39, 115.93, 120.08, 120.85, 121.73, 123.13, 123.97, 124.64, 124.75, 126.89, 128.16, 137.96, 138.56, 142.07, 142.22, 146.76, 147.40, 149.58, 149.78, 151.65, 151.99, 155.44.

Example 19

Upon preparation of and analysis of the emission spectra of thin films prepared from Composition A (PtON1)

photoluminescent quantum yield measurements suggested quenching interactions between the dopant and host material of the composition. In contrast, thin films prepared from Composition B (PtON6)

can exhibit beneficial photoluminescent properties without comprising excited state energy or lifetimes. Thus, substitution of a phenyl ring on the pyrazole of Composition A can be a useful substitution to improve the photoluminescent properties of the material and to potentially increase stability by extending conjugation of the pyrazole ring. Photoluminescent (PL) spectra for Composition A and Composition B in room temperature 2-methyltetrahydrofuran solution are shown in FIG. 15, where Composition B exhibits more vibronic character and bluer and narrower emission compared to Composition A. FIG. 16 shows a comparison of the emission spectra for the two compounds as doped into a polymethylmethacrylate (PMMA) optically inert matrix. As shown, the highest energy peak for both Composition A and Composition B are identical, indicating that phenyl substitution does not result in any significant red-shift in the emission spectra. Composition B exhibits a narrower emission spectrum having a more desirable blue emission. Both compounds exhibit a photoluminescent quantum yield (PLQY) in PMMA of about 80%. The excited state lifetime in a 77 K 2-methyltetrahydrofuran solution for Composition B is 9.3 microseconds compared to 9.7 microseconds for Composition A. In summary, phenyl substitution does not negatively affect the PLQY or dramatically increase the excited state lifetime by enabling a more ligand based emission.

Example 20

As described in this example, molecular phosphorescent emitters with FWHM values of less than 30 nm can be prepared and color-tuned in a full visible spectrum through a judicious molecular design and can demonstrate a peak electron-to-photon conversion efficiency close to unity in a device setting. To develop organic thin film devices with narrow-band EL spectra, current research efforts focus on developing various LEDs using colloidal quantum dots (QDs) as the emissive layers. For example, CdSe(ZnS) nanocrystal QDs can be continuously tunable crossing the visible spectrum, with a high PL quantum efficiency and a FWHM value less than 30 nm, yet, the synthetic condition of QDs needs to be strictly controlled in order to prevent a larger particle size distribution and maintain a narrow emission spectral bandwidth. Nevertheless, QD-based LEDs have progressed rapidly in the past decade with reported device efficiency over 18% for red LEDs and reasonable device operational stability. However, blue QD LEDs remain a big challenge due to the stringent constraints on the small particle size and uniformity. Typically, blue QD LEDs exhibit very low external quantum efficiencies of much less than 1%, although a few recent reports have demonstrated greater external quantum efficiencies, with the highest reported to date of 7.1% which is much lower than state-of-the-art deep blue OLEDs (˜20%). Additionally, there is no clear solution to solve the problem of poor interfacial energy barriers between QD emissive layers and organic transporting layers, and furthermore, the energy transfer processes at these interfaces remains poorly understood.

To overcome these inherent problems with QDs, it is desirable to fabricate OLEDs using an organic emitter with a narrow emission spectral bandwidth (or a narrow-band emission). A narrow-band emission spectrum can be easily achieved if the radiative decay process originates from atomic excited states as in lanthanide complexes, in which the emission bands as well as absorption bands (f-f transitions) are extremely sharp, in the range of 10-15 nm. However, these emitters have not demonstrated high electron-to-photon conversion efficiency in devices due to inefficient energy transfer from organic ligand to lanthanide metal ions as well as poor energy transfer process between host materials and lanthanide based emitters. Similarly, rigid macrocyclic complexes like 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum(II) (PtOEP) have also demonstrated narrow-band emission with a FWHM of around 20 nm. Although PtOEP has demonstrated an early promise of utilization as phosphorescent emitters for OLEDs, further development has been hindered by its long-lived triplet lifetime (in the range of 100 μs) and large difficulty in structural modification for color-tuning of porphine materials. On the other hand, cyclometalated Ir and Pt complexes have high luminescent quantum yields and comparatively short phosphorescent lifetimes due to strong spin-orbit coupling, making them ideal emissive dopants in OLEDs. By harvesting all the electro-generated triplet and singlet excitons, carefully designed devices have demonstrated emission with nearly 100% internal quantum efficiency (IQE). Moreover, efficient OLEDs ranging from blue to red have been reported through a careful selection of the cyclometalating ligands. One outstanding issue with this class of complexes, however, is that they typically exhibit broad emission spectra making them non-ideal for display applications. Thus, it will be extremely desirable to further develop cyclometalated Ir and Pt complexes having small FWHM values with a judicious molecular design in order to develop efficient organic EL devices with narrow-band emission tunable across the visible spectrum.

The shape and spectral bandwidth of the emission and absorption spectra of phosphorescent emitters are directly determined by the properties of the ground state and the lowest excited state. To achieve narrow bandwidth it is preferred to have a single dominant peak which has narrow atomic-like radiative transitions. It is well documented that the luminescence from cyclometalated Ir(III) and Pt(II) complexes originates from a lowest triplet excited (T₁) state that is a ligand centered charge transfer state (³LC) with metal-to-ligand-charge-transfer characters (¹MLCT/³MLCT) mixed in through spin-orbit coupling. At room temperature most of these complexes exhibit either broad Gaussian-shape emission, if the T₁ state has a majority of ³MLCT character, or have an emission spectrum with vibronic features, when its T₁ state mainly consisting of ³LC characters; neither of which are conducive to narrow band emission. However, if an emitter has a rigid molecular structure with a single dominant vibrational stretch, it will show an emission spectrum with more pronounced vibronic features. Moreover, if the Hang-Rys factor (S_(M)), which is characterized as the intensity ratio of this first major vibrational transition to the highest energy peak, is minimized, the emission spectrum of phosphorescent emitters will have much smaller FWHM values, resembling to the emission spectrum of QDs.

Following this proposed molecular design principle, PtN1N is prepared as a green-emitting phosphorescent emitter with a FWHM of 18 nm and a S_(M) value of 0.3 at room temperature. The chemical structure of PtN1N is illustrated in the inset of FIG. 17A, where the tetradentate cyclometalating ligand is designed to include a rigid ligand of pyrazolyl-carbazole (functioning as a lumophore) bonded to pyridyl-carbazole (functioning as an ancillary ligand). The choice of ancillary ligands needs to be carefully selected in order to prevent the localization of the T₁ state on the ancillary ligand and minimize the S_(M) value by controlling the properties of the T₁ state. The room temperature and 77 K emission spectra of PtN1N and its analogs are shown in FIG. 17A. Due to the selection of similar lumophores, both PtN1pyC1 and PtN1acac have similar emission spectra at 77K to PtN1N in terms of emission energies and vibronic spacing energies of emission spectra, as shown in FIGS. 17B and 17C. The room temperature and 77 K emission spectra of PtN1ppy, however, as shown in FIG. 17D, are drastically different, which indicates a different T₁ state for PtN1ppy due to its improper choice of ligands bonded to the designated lumophore. Despite their similar emission energies, PtN1acac has a much larger S_(M) value (0.4) than those of PtN1N (0.2) and PtN1pyC1 (0.3) at low temperature. Such a difference can be attributed to the different properties of the T₁ states, which are affected by the degree of ¹MLCT characters mixed with ³LC characters and can be related to the selection of cyclometalating ligand. Moreover, a larger variation in their emission spectra was observed at the room temperature for these three compounds. In addition to its narrow-band emission, the tetradentate Pt complex, PtN1N, also has a higher emission quantum yield (Φ=0.81) than its bidentate analog, i.e. PtN1acac (Φ=0.03) and its tridentate analog, i.e. PtN1pyC1 (Φ=0.03). Furthermore, the PL quantum efficiency of PtN1N in a doped PMMA film is experimentally determined to be 0.90±0.05, close to unity.

To evaluate the electroluminescent properties of PtN1N, a series of OLEDs were fabricated in a 5-layer device structure: PEDOT:PSS/NPD/TAPC/x % PtN1N:26mCy/PO15/BmPyPB/LiF/Al, with the dopant concentration ranging from 2-14%. The EL spectra and forward viewing external quantum efficiency is plotted versus brightness for these devices in FIGS. 18A-18D. Similar to the previously reported phosphorescent OLEDs, increasing the dopant concentration slightly lowers the driving voltage and exhibited a smaller efficiency roll-off as a result of improved charge carrier balance. Moreover, increasing high dopant concentration maintains high device efficiency and the 14% PtN1N device demonstrated an extremely high maximum forward viewing EQE of η_(ext)=25.6% at a brightness of 10 cd/cm², and only decreases slightly to η_(ext)=25.5% at a high forward viewing luminance of 100 cd/m². This device also gives a maximum forward power efficiency of η_(p)=66.5 lm/W and remains at a high η_(p)=48.5 lm/W at a practical luminance (100 cd/m²) for displays. These efficiencies are among the highest reported for OLEDs without any outcoupling enhancement architecture, representing an approximately 100% internal quantum efficiency. More importantly, the PtN1N retained the impressive narrow band emission in the device setting resulting in a FWHM value of only 18 nm for the 2% PtN1N device. Additionally, excimer emission was not observed at increased dopant concentrations and the EL spectra of PtN1N devices are not significantly broadening with FWHM values only increasing to 22 nm.

The stability of PtN1N as a phosphorescent emitter was tested using a known stable device structure: ITO/HATCN (10 nm)/NPD(40 nm)/x % PtN1N:CBP (25 nm)/BAlq (10 nm)/Alq (40 nm)/LiF/Al. The device efficiency, shown in FIG. 19A, drops considerably compared to our previously optimized device due to the lack of state-of-the-art stable host and blocker materials. Thus, at any given current density the amount of light extracted from the device is significantly lower than in a more efficient structure but such devices will still provide valuable information on the electrochemical stability of PtN1N in a device setting: this is a strong indication for the potential commercialization of such class of materials. Furthermore, due to poor charge balance in this stable structure and the lack of efficient charge and exciton confining materials, there is a large drop off in peak efficiency from 10.0% to 4% as the dopant concentration is increased from 6% to 20%, which ultimately yields lower lifetimes (when corrected for elevated initial luminance) for the devices with higher dopant concentrations. In FIG. 19B, the relative luminance versus time is plotted for devices operated at a constant current of 20 mA/cm² which corresponds to an initial luminance (L₀) in the range of 2200-3550 cd/m². It is very encouraging to report that the lifetime at 70% initial luminance, LT₇₀, of 6%, 10%, and 20%-doped PtN1N devices are 46.5 hrs (L₀=3550 cd/m²), 53.5 hours (L₀=3500 cd/m²) and 70 hrs (L₀=2200 cd/m²) respectively. This can be translated to a LT₇₀ at 100 cd/m² of over 18,000 hrs for the 20% device and 32,000 hrs for the 10% device using the formula LT(L₁)=LT(L₀)*(L₀/L₁)^(1.8), which is approaching the requirement for potential commercialization at an early stage. Much improvement will be expected with the incorporation of more advanced host and blocking materials in optimized device architectures. This result is comparable to the best reported lifetimes for red emitting platinum complexes and is a significant improvement from the previous report on blue or green platinum based emitters, thus this molecular design method should serve as a major step forward in the development of stable platinum based phosphorescent emitters for OLEDs applications.

Following a similar materials design principle, a series of narrow-band phosphorescent emitters were developed with emission colors across the visible spectrum. Although the frame of the tetradentate cyclometalated complex structure is maintained, the lumophores were modified individually to phenyl methyl-imidizolyl group for blue-emitting PtON7-t-Bu, methyl-imidizolyl carbazolyl group for bright green-emitting PtN7N and benzo-methyl-imidizolyl carbazolyl group for orange-emitting PtN8ppy. Moreover, in order to ensure a narrow-band emission, the components of ancillary ligands were also modified accordingly to t-butyl-pyridyl carbazole for blue-emitting PtON7-t-Bu and phenyl-pyridine for orange-emitting PtN8ppy. The room temperature emission spectra and the chemical structures of PtON7-t-Bu, PtN7N and PtN8ppy are shown in FIGS. 20A and 20D. The highly saturated colors from our developed narrowband phosphorescent emitters enable us to achieve the color coordinates within proximity to the blue and green points in the CIE chromaticity diagram. Moreover, all of the Pt complexes have high quantum efficiency in solution (Table 1) and have also demonstrated high device efficiencies of close to 20% in the device settings for the deep-blue emitting and orange-emitting devices (FIG. 20B). The CIE coordinates of the PtON7-t-Bu device (0.14, 0.09) is very close to the National Television Systems Committee (NTCS) standards for blue (0.14, 0.08) which is noteworthy since few reports have ever demonstrated a CIE_(y) coordinate of less than 0.1. Furthermore, the PtON7-t-Bu device has a much higher device efficiency that any previously reported deep blue OLED with a CIEy value of less than 0.1. This achievement is attributed to the fact that most deep blue emitting OLEDs with such desirable CIE coordinates, such as Ir(fppz)₂(dfbdp), which achieved 11.7% peak EQE and CIE of (0.155, 0.106), or Ir(pmb)₃, which achieved 5.8% peak EQE and CIE of (0.17, 0.06), require strong emission peaks between 380-450 nm due to its broad tail or large sideband extending into the blue-green or green portion of the visible spectrum. Due to the narrow emission spectrum of PtON7-t-Bu, as seen in FIG. 20C, devices can achieve highly desirable color without having to dramatically shift the primary emission energy to the UV-Blue or deep-blue region. This lower energy emission avoids potential quenching by either the host or blocker materials and does not require the use of ultra-high bandgap materials, which is essential for both high efficiencies and long operational lifetimes. This result highlights the benefits and importance of narrow-band emitters to tune the emission to the precise colors desired in order to achieve the most efficient and high color purity devices possible.

TABLE 1 Photophysical properties of PtN1N and its analogs in a solution of dicholoromethane at room temperature and in a solution of 2-methyl THF at 77 K. Emission at RT Emission at 77 K λ_(max) FWHM Φ τ λ_(max) τ Complex (nm) (nm) (%) (μs) (nm) (μs) PtN1(acac) 516 75 3 9.9 464 74.5 PtN1pyCl 482 18 3 2.3 478 52.4 PtN1ppy 544 68 13 1.4 524 5.9 PtN1N 491 18 81 12.9 484 14.4 PtON7-t-Bu 446 20 83 6.6 439 8.2 PtN7N 510 18 61 10.9 503 12.3 PtN8ppy 573 26 40 3.4 564 7.7

Thus, a very efficient organic electrophosphorescent device with a FWHM value of EL spectra less than 20 nm and an IQE of close to unity has been fabricated. Such a molecular engineering method was applied to prepare a series of narrow-band phosphorescent complexes emitting efficiently across the whole visible spectrum. Additionally, the emissive materials described herein are halogen-free phosphorescent emitters that demonstrate impressive device operational lifetimes estimated in the range of 15,000 to 30,000 hours at a practical luminance of 100 cd/m² and integration with state-of-the-art stable host, blocking, and transporting materials should yield even greater device performance and operational lifetimes. Furthermore, a deep blue narrow band emitter had a peak EQE of 17.6% while exhibiting excellent CIE coordinates of (0.14, 0.09), the highest among the few reported devices which achieved a CIE_(y) value of less than 0.1.

Methods.

Steady state emission experiments at both 77K and room temperature were performed on a Horiba Jobin Yvon FluoroLog-3 spectrometer. Solution quantum efficiency measurements were carried out at room temperature in a solution of dichloromethane which were thoroughly bubbled with nitrogen inside of a glove box with an oxygen content less than 1 ppm. Solutions of coumarin 47 (coumarin 1, Φ=0.73)⁴⁹ in ethanol were used as a reference. The equation

$\Phi_{s} = {\Phi_{r}\left( \frac{\eta_{s}^{2}A_{r}I_{s}}{\eta_{r}^{2}A_{s}I_{r}} \right)}$ was used to calculate the quantum yields where s denotes the sample, r the coumarin reference, Φ the quantum yield, η the refractive index, A the absorbance, and I the integrated area of the emission band.⁵⁰ Phosphorescence lifetime measurements were performed on the same spectrometer with a time correlated single photon counting method using a LED excitation source. The absolute PL quantum efficiency measurements of doped PMMA film were carried out on a Hamamatsu C9920 system equipped with a xenon lamp, integrating sphere and a model C10027 photonic multi-channel analyzer.

Devices were fabricated on ITO coated glass substrates. PEDOT:PSS was filtered through a 0.2 μm filter and spin-coated on the precleaned substrates, giving a 40-50 nm thick film. All other materials were deposited in a glove-box hosted vacuum deposition system at a pressure of 10⁻⁷ torr. I-V-L characteristics were taken with a Keithley 2400 Source Meter and a Newport 818 Si photodiode. All device operation and measurement were carried out inside a nitrogen-filled glove-box. Individual devices had areas of 0.04 cm². Electroluminescence (EL) spectra were taken using the Jobin Yvon Fluorolog-3 spectrometer. Agreement between luminance, optical power and EL spectra was verified with a calibrated Photo Research PR-670 Spectroradiometer with all devices assumed to be Lambertian emitters.

The materials used have acronyms as follows. HATCN: 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile. NPD: N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4″-diamine. TAPC: di-(4-N,N-ditolyl-amino-phenyl)cyclohexane. 26mCPy: 2,6-bis(N-carbazolyl) pyridine. DPPS: diphenyl-bis[4-(pyridin-3-yl)phenyl]silane. BmPyPB: 1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene. PO15: 2,8-bis(diphenylphosphoryl)-dibenzothiophene. CBP: 4,4′-bis(N-carbazolyl) biphenyl. BAlq: bis(2-methyl-8-quinolinolato) (biphenyl-4-olato)aluminum. Alq: tris-(8-hydroxyquinoline) aluminum. The layer sequence for OLEDs containing PtN1N of various concentrations are as below: ITO/PEDOT:PSS/NPD (30 nm)/TAPC (10 nm)/x % PtN1N:26mCPy (25 nm)/PO15 (10 nm)/BmPyPB (30 nm)/LiF (1 nm)/Al (90 nm) where x is either 2%, 7%, or 14% dopant concentration by mass. For the stability devices the following structure was used: ITO/HATCN (10 nm)/NPD (40 nm)/x % PtN1N: CBP (25 nm)/BAlq (10 nm)/Alq (30 nm)/LiF/Al where x is either 6%, 10% or 20% dopant concentration. For devices employing the various emitters across the visible spectrum the following structure was used: ITO/HATCN (10 nm)/NPD (40 nm)/TAPC (10 nm)/x % dopant:26mCPy (25 nm)/DPPS (10 nm)/BmPyPB (40 nm)/LiF (1 nm)/Al (90 nm) where the dopant is either PtN1N, PtON7-t-Bu, or PtN8ppy.

Table 2 provides a summary of device characteristics at peak value and 100 cd/m² for the devices with two different structures. Device type I: PEDOT:PSS/NPD/TAPC/x % PtN1N: 26mCPy/PO15/BmPyPB/LiF/Al. Device type II: ITO/HATCN/NPD/TAPC/x % emitter:26mCPy/DPPS/BmPyPB/LiF/Al.

TABLE 2 Device characteristics η_(EQE) η_(A) η_(P) λ_(max) FWHM @ 100 @ 100 @ 100 EML (nm) (nm) CIE peak cd/m² peak cd/m² peak cd/m² 2% PtN1N^(I) 496 18 (0.13, 0.55) 23.5 21.7 59.1 54.7 50.3 42.9 7% PtN1N^(I) 498 20 (0.15, 0.56) 26.1 25.8 68.7 67.7 61.7 56.3 14% PtN1N^(I) 498 22 (0.15, 0.58) 25.6 25.5 70.5 70.2 67.3 61.1 8% PtN1N^(II) 498 22 (0.14, 0.60) 25.1 21.9 69.3 60.7 66.5 48.5 6% PtON7-t-Bu^(II) 450 28 (0.14, 0.09) 17.6 10.7 15.2 9.3 14.4 5.3 2% PtN8ppy^(II) 576 28 (0.53, 0.47) 19.3 16.0 60.4 50.2 48.3 29.1

Synthesis of PtN1N: To a dry pressure tube equipped with a magnetic stir bar, add 2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole (1427 mg, 3.0 mmol, 1.0 eq), K₂PtCl₄ (1308 mg, 3.15 mmol, 1.05 eq), ^(n)Bu₄NBr (97 mg, 0.3 mmol, 0.1 eq), and acetic acid (180 mL) in a nitrogen-filled glove box. The mixture was bubbled with nitrogen for 30 minutes, sealed before being taken out of the glove box, and stirred at room temperature for 20 hours followed by three days at 105-115. The mixture was cooled down to ambient temperature and water (180 mL) was added slowly. After stirring at room temperature for 10 minutes, the precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent to obtain the desired product PtN1N as a yellow solid 872 mg in 44% yield. (Note: This reaction was carried out several times, and the yields were 27-51%.) ¹H NMR (DMSO-d₆, 400 MHz): δ 6.86 (t, J=2.0 Hz, 1H), 7.30 (t, J=7.6 Hz, 1H), 7.40-7.44 (m, 2H), 7.48-7.52 (m, 2H), 7.70 (d, J=8.4 Hz, 1H), 7.95 (d, J=8.0 Hz, 1H), 8.00 (d, J=8.0 Hz, 1H), 8.07 (d, J=8.0 Hz, 1H), 8.10 (d, J=2.0 Hz, 1H), 8.14 (d, J=8.0 Hz, 1H), 8.20-8.27 (m, 5H), 8.90 (d, J=2.8 Hz, 1H), 9.20 (d, J=5.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 106.00, 107.65, 108.24, 11.58, 113.00, 113.54, 114.40, 115.31, 115.35, 116.47, 116.93, 118.27, 120.19, 120.45, 120.59, 120.91, 122.89, 125.09, 125.59, 126.09, 127.48, 128.87, 137.97, 138.21, 138.27, 139.28, 139.91, 140.23, 143.32, 143.35, 147.26, 151.84. Anal. Calcd. for C₃₂H₁₉N₅Pt: C, 57.48, H, 2.86, N, 10.47; Found: C, 57.29, H, 3.06, N, 10.39.

Synthesis of PtON7-t-Bu: To a dry pressure vessel equipped with a magnetic stirr bar, add 1-(3-(9-(4-tert-butylpyridin-2-yl)-9H-carbazol-2-yloxy)phenyl)-3-meth-yl-1H-imidazol-3-ium hexafluorophosphate(V) (1.28 g, 3.69 mmol, 1.0 eq), Pt(COD)Cl₂ (1.50 g, 4.00 mmol, 1.09 eq), NaOAc (0.93 g, 11.34 mmol, 3.1 eq) and solvent THF (150 mL) in a nitrogen filled glove box. The mixture was bubbled with nitrogen for 15 minutes, sealed before being taken out of the glove box, and stirred at a temperature of 120° C. in an oil bath for three days. After cooling down to ambient temperature, the solvent was removed in vacuum and the remaining solid was dissolved in DCM. The insoluble solid in the solution was filtered off and the filtrate was concentrated under reduced pressure. The residue was purified through column chromatography on neutral Al₂O₃ using dichloromethane as eluent to obtain the desired product PtON7-t-Bu as a brown solid 0.70 g in 28% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 1.30 (s, 9H), 3.85 (s, 3H), 6.88 (d, J=8.0 Hz, 1H), 7.13 (t, J=7.6 Hz, 1H), 7.19-7.24 (m, 3H), 7.37 (t, J=7.2 Hz, 1H), 7.45-7.49 (m, 2H), 7.85 (d, J=8.4 Hz, 1H), 8.01 (d, J=2.0 Hz, 1H), 8.04 (d, J=4.8 Hz, 1H), 8.05 (s, 1H), 8.13 (d, J=7.2 Hz, 1H), 9.04 (d, J=6.4 Hz, 1H). ¹³C NMR (DMSO-d₆, 100 MHz): δ 29.61, 35.35, 36.84, 109.91, 110.61, 122.10, 122.46, 123.00, 114.44, 114.97, 115.79, 115.88, 116.31, 117.06, 120.02, 122.60, 122.79, 124.24, 124.35, 128.00, 138.20, 143.07, 148.31, 149.17, 151.84, 153.45, 155.70, 163.48, 181.91. MS (MALDI-TOF) for C₃₁H₂₆N₄OPt [M]⁺: calcd 665.18, found 665.32.

Synthesis of PtN7N: 3-methyl-1-(9-(pyridin-2-yl)-9H-2,9′-bicarbazol-2′-yl)-1H-imidazol-3-ium hexafluorophosphate(V) (95 mg, 0.15 mmol, 1.0 eq), PtCl₂ (40 mg, 0.15 mmol, 1.0 eq) and DMF (10 mL) solvent were added a pressure tube equipped with a magnetic stir bar in a nitrogen filled glove box. The pressure tube was sealed and the mixture was stirred in an oil bath at a temperature of 120° C. for three days and then cooled down to ambient temperature. The mixture was poured into water (20 mL), then extracted with dichloromethane (20 mL×3). The combined organic layer was washed with water (10 mL×3), dried over sodium sulphate, filtered and the filtrate was concentrated under reduced pressure. The residue was purified through column chromatography on neutral Al₂O₃ using dichloromethane as eluent to obtain the desired product PtN7N as a yellow solid 15 mg in 15% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 3.85 (s, 3H), 7.21-7.29 (m, 2H), 7.38-7.45 (m, 4H), 7.47-7.51 (m, 1H), 7.83 (d, J=7.6 Hz, 1H), 7.96 (d, J=8.0 Hz, 1H), 8.02-8.08 (m, 3H), 8.13 (d, J=7.6 Hz, 1H), 8.15-8.19 (m, 4H), 9.52 (d, J=5.6 Hz, 1H). ¹³C NMR (DMSO-d₆, 125 MHz): δ 36.68, 106.04, 112.05, 112.52, 113.31, 114.35, 114.75, 115.52, 116.23, 116.44, 116.49, 118.69, 119.69, 120.04, 120.14, 120.59, 122.42, 122.65, 124.86, 125.37, 126.38, 126.69, 127.63, 138.38, 138.77, 139.31, 139.34, 140.34, 143.99, 146.40, 147.95, 155.21, 180.14. Anal. Calcd. for C₃₃H₂₁N₅Pt.H₂O: C, 56.57, H, 3.31, N, 10.00; Found: C, 56.59, H, 3.75, N, 10.18.

Synthesis of PtN8ppy: To a dry pressure tube equipped with a magnetic stir bar, add 2-(1-methyl-1H-benzo[d]imidazol-2-yl)-9-(3-(pyridin-2-yl)phenyl)-9H-carbazole (345 mg, 0.77 mmol, 1.0 eq), K₂PtCl₄ (350 mg, 0.84 mmol, 1.1 eq), ^(n)Bu₄NBr (21 mg, 0.077 mmol, 0.1 eq), and acetic acid (46 mL) in a nitrogen filled glove box. The mixture was bubbled with nitrogen for 30 minutes, sealed before being taken out of the glove box, and stirred in an oil bath at a temperature of 108-115° C. for three days. The mixture was cooled down to ambient temperature and water (90 mL) was added slowly. The precipitate was filtered off and washed with water three times. Then the solid was dried in air under reduced pressure. The collected solid was purified through column chromatography on silica gel using dichloromethane as eluent. The filtrate was concentrated and the black precipitate was filtered off, then dried under reduced pressure to obtain the desired product PtN8ppy 23.4 mg in 5% yield. ¹H NMR (DMSO-d₆, 400 MHz): δ 4.37 (s, 3H), 7.31 (t, J=6.4 Hz, 1H), 7.38-7.46 (m, 3H), 7.50-7.54 (m, 1H), 7.68 (t, J=6.4 Hz, 1H), 7.78 (d, J=7.2 Hz, 1H), 7.86-7.88 (m, 1H), 7.91 (d, J=6.8 Hz, 1H), 7.96 (d, J=8.0 Hz, 1H), 8.01 (d, J=8.0 Hz, 1H), 8.12 (d, J=8.0 Hz, 1H), 8.17-8.21 (m, 1H), 8.26-8.31 (m, 3H), 9.43 (d, J=5.2 Hz, 1H). Anal. Calcd. for C₃₁H₂₀N₄Pt: C, 57.85, H, 3.13, N, 8.71; Found: C, 57.49, H, 3.46, N, 8.56.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims. 

What is claimed is:
 1. A composition comprising one or more of the compounds selected from:


2. A device comprising the composition of claim
 1. 3. The device of claim 2, wherein the device comprises a full color display.
 4. The device of claim 2, wherein the device is a photovoltaic device.
 5. The device of claim 2, wherein the device is a luminescent display device.
 6. The device of claim 2, wherein the device comprises an organic light emitting diode (OLED).
 7. The device of claim 6, wherein the device comprises a phosphorescent organic light emitting diode.
 8. The device of claim 6, wherein the device is a phosphorescent organic light emitting diode.
 9. A light emitting device comprising the composition of claim
 1. 10. A compound having the following structure:


11. A compound having the following structure: 